Even if you don't have the brain power to concentrate on this stuff, the books are still fun to read as they demonstrate examples.? A few times, I would hang out with my friend Walter, and we would bring out some BYTE or old Popular Electronics magazines and just read through articles, pointing out some interesting hind sight observations.? I'm looking forward to my retirement years!
On Monday, May 10, 2021, 10:46:16 a.m. EDT, Bill in OKC too via groups.io <wmrmeyers@...> wrote:
You can find a lot of them as PDF files on archive.org, along with a lot of the other classic computer & programming books. Zak's, Osbourne, and others,? tech manuals from the manufacturers, etc.
I don't know if I have the brainpower to actually use them anymore, but have downloaded a bunch of them myself.
Bill in OKC
William R. Meyers, MSgt, USAF(Ret.)
A human being should be able to change a diaper, plan an invasion,
butcher a hog, conn a ship, design a building, write a sonnet, balance
accounts, build a wall, set a bone, comfort the dying, take orders,
give orders, cooperate, act alone, solve equations, analyze a new
problem, pitch manure, program a computer, cook a tasty meal, fight
efficiently, die gallantly. Specialization is for insects.
LAZARUS LONG (Robert A. Heinlein)
On Monday, May 10, 2021, 08:49:42 AM CDT, saturn5tony via groups.io <saturn5tony@...> wrote:
On Sun, May 9, 2021 at 10:28 PM, joshbensadon wrote:
You can only truly appreciate the Z80 when you start using the Repetitive Copy and Compare instructions.?
?
Are you reading any books on the Zed-80?
?
Hi Josh, I dont remember that instruction, but I know it had quite a few more that were better than the old 8080 as well as an improved register set. I know that the HW took the 3 power supplies from 3 down to 5V only. Really great for that time. IIRC I think that is why Intel came out with the 8085? Wow so many years ago, I am mixing up what they did back then. As I read frm down below, I also mixed up the company names as well. LOL!! I think I was on the 6800 - 6502 path in my mind, not on the 8080 - Z80 path. So many things happened back then. Now so little memory left of what happened as well I believe. HEHE--thank God I am not a writer of computer history and such! lol As far as books, all I have left relating to the Z80 was the one I got back in the early 80's called "the Z80 microcomputer handbook" by Wlliam Barden jr. I read a bit of it back then when were designing a computer system for a new product that were making but went to the 8048, 8031 and other MCS51 stuff for our final design. I was not into home pc's back then so much for my career but into more controller applications that we were doing. MCS51 rocked the world for us. Home use I went from 1802 and 6502 stuff. Why, I really have no idea. I guess I just liked them all.
|
You can find a lot of them as PDF files on archive.org, along with a lot of the other classic computer & programming books. Zak's, Osbourne, and others,? tech manuals from the manufacturers, etc.
I don't know if I have the brainpower to actually use them anymore, but have downloaded a bunch of them myself.
Bill in OKC
William R. Meyers, MSgt, USAF(Ret.)
A human being should be able to change a diaper, plan an invasion,
butcher a hog, conn a ship, design a building, write a sonnet, balance
accounts, build a wall, set a bone, comfort the dying, take orders,
give orders, cooperate, act alone, solve equations, analyze a new
problem, pitch manure, program a computer, cook a tasty meal, fight
efficiently, die gallantly. Specialization is for insects.
LAZARUS LONG (Robert A. Heinlein)
On Monday, May 10, 2021, 08:49:42 AM CDT, saturn5tony via groups.io <saturn5tony@...> wrote:
On Sun, May 9, 2021 at 10:28 PM, joshbensadon wrote:
You can only truly appreciate the Z80 when you start using the Repetitive Copy and Compare instructions.?
?
Are you reading any books on the Zed-80?
?
Hi Josh, I dont remember that instruction, but I know it had quite a few more that were better than the old 8080 as well as an improved register set. I know that the HW took the 3 power supplies from 3 down to 5V only. Really great for that time. IIRC I think that is why Intel came out with the 8085? Wow so many years ago, I am mixing up what they did back then. As I read frm down below, I also mixed up the company names as well. LOL!! I think I was on the 6800 - 6502 path in my mind, not on the 8080 - Z80 path. So many things happened back then. Now so little memory left of what happened as well I believe. HEHE--thank God I am not a writer of computer history and such! lol As far as books, all I have left relating to the Z80 was the one I got back in the early 80's called "the Z80 microcomputer handbook" by Wlliam Barden jr. I read a bit of it back then when were designing a computer system for a new product that were making but went to the 8048, 8031 and other MCS51 stuff for our final design. I was not into home pc's back then so much for my career but into more controller applications that we were doing. MCS51 rocked the world for us. Home use I went from 1802 and 6502 stuff. Why, I really have no idea. I guess I just liked them all.
|
On Sun, May 9, 2021 at 10:28 PM, joshbensadon wrote:
You can only truly appreciate the Z80 when you start using the Repetitive Copy and Compare instructions.?
?
Are you reading any books on the Zed-80?
?
Hi Josh, I dont remember that instruction, but I know it had quite a few more that were better than the old 8080 as well as an improved register set. I know that the HW took the 3 power supplies from 3 down to 5V only. Really great for that time. IIRC I think that is why Intel came out with the 8085? Wow so many years ago, I am mixing up what they did back then. As I read frm down below, I also mixed up the company names as well. LOL!! I think I was on the 6800 - 6502 path in my mind, not on the 8080 - Z80 path. So many things happened back then. Now so little memory left of what happened as well I believe. HEHE--thank God I am not a writer of computer history and such! lol As far as books, all I have left relating to the Z80 was the one I got back in the early 80's called "the Z80 microcomputer handbook" by Wlliam Barden jr. I read a bit of it back then when were designing a computer system for a new product that were making but went to the 8048, 8031 and other MCS51 stuff for our final design. I was not into home pc's back then so much for my career but into more controller applications that we were doing. MCS51 rocked the world for us. Home use I went from 1802 and 6502 stuff. Why, I really have no idea. I guess I just liked them all.
|
You can only truly appreciate the Z80 when you start using the Repetitive Copy and Compare instructions.? With a single instruction, you can move a block of 64K as fast as the memory read/write cycles will permit.? Of course, that's the whole memory map and while that might be a useful thing (say your hardware can bank switch between reads and writes?)? it's more likely to do smaller chunks of data.? The speed increase to move blocks of data like this is really significant!
Are you reading any books on the Zed-80?
On Sunday, May 9, 2021, 10:14:08 a.m. EDT, saturn5tony via groups.io <saturn5tony@...> wrote:
On Sun, May 9, 2021 at 08:26 AM, joshbensadon wrote:
Good luck on your Z80MC build.? The "zed 80" was quite a successful processor.?
Hi Josh, Thank you so much for approving me. Yea, I did not really do enough with that processor years ago (so much changed afterwards as I am sure you all know) but I did see how many systems were created by it and did read a small bit about its architecture. A truly awesome micro. It will be so much fun to now get back into it. See you online! -Tony
|
On Sun, May 9, 2021 at 08:26 AM, joshbensadon wrote:
Good luck on your Z80MC build.? The "zed 80" was quite a successful processor.?
Hi Josh, Thank you so much for approving me. Yea, I did not really do enough with that processor years ago (so much changed afterwards as I am sure you all know) but I did see how many systems were created by it and did read a small bit about its architecture. A truly awesome micro. It will be so much fun to now get back into it. See you online! -Tony
|
Hi Tony,
Good luck on your Z80MC build.? The "zed 80" was quite a successful processor.? It's line up of peripheral chips made it very much a dream machine.? The fact that it had all these great registers and was backward compatible with the 8080 (mostly) made it a very interesting solution for new and old systems.
Cheers,
Josh
On Saturday, May 8, 2021, 07:34:11 p.m. EDT, saturn5tony via groups.io <saturn5tony@...> wrote:
Sorry for the silly joke above. Yea hello guys! Yup.. a new Z80 freak here, lol. Not really a user of the zed 80 other than having a Microsoft Z80 card (that I still have) in my Apple IIe. (apparently Bill wanted 350 bucks for this card!) I am an old developer (turned to sw as of the last few dozen years or so) and one that loved electronics from the 70's and now retired. Also enjoying retro computers of all kind. I have been on the 1802 side for a while here but found out about Lee and his awesome designs for every micro we had .. from back in the day. (Hi Lee) and just bought the Z80MC and in the process of building it. Man I love the LEDs here as well as the IO card. Very cool stuff. So yea I got the SIO card too. Looking to build it soon and having fun with this retro "uC" from the past (cant beat the cool Docs too Lee) and hope I may be able to contribute to this group as well. Please excuse my typing here and there, I have some cognitive issues and hope you wont mind. Thanks for reading and accepting me into the power of what those old ex-motorola guys saw back in those days that we loved so much.? (Note: I am not biased by any micro, I do have a life time appreciation for them all!)Well maybe I am a bit biased on this paper microcomputer....  ? hehe, no not really jk! Back in the 70's I was going to get this. But I was building an 8008 micro at the time, making some texas towers and thought, hmmm maybe I'll leave it to those that want to learn about them. Did I know about them... NO, could I build one.. yes. LOL, yea Hackaday has a great article about it too. Go Cardiac! So thats my silly bio for the moment, hope to meet you all and lets push some more 1's and 0's around! See ya! Tony
|
Sorry for the silly joke above. Yea hello guys! Yup.. a new Z80 freak here, lol. Not really a user of the zed 80 other than having a Microsoft Z80 card (that I still have) in my Apple IIe. (apparently Bill wanted 350 bucks for this card!) I am an old developer (turned to sw as of the last few dozen years or so) and one that loved electronics from the 70's and now retired. Also enjoying retro computers of all kind. I have been on the 1802 side for a while here but found out about Lee and his awesome designs for every micro we had .. from back in the day. (Hi Lee) and just bought the Z80MC and in the process of building it. Man I love the LEDs here as well as the IO card. Very cool stuff. So yea I got the SIO card too. Looking to build it soon and having fun with this retro "uC" from the past (cant beat the cool Docs too Lee) and hope I may be able to contribute to this group as well. Please excuse my typing here and there, I have some cognitive issues and hope you wont mind. Thanks for reading and accepting me into the power of what those old ex-motorola guys saw back in those days that we loved so much.? (Note: I am not biased by any micro, I do have a life time appreciation for them all!)Well maybe I am a bit biased on this paper microcomputer....  ? hehe, no not really jk! Back in the 70's I was going to get this. But I was building an 8008 micro at the time, making some texas towers and thought, hmmm maybe I'll leave it to those that want to learn about them. Did I know about them... NO, could I build one.. yes. LOL, yea Hackaday has a great article about it too. Go Cardiac! So thats my silly bio for the moment, hope to meet you all and lets push some more 1's and 0's around! See ya! Tony
|
Re: SD I/O 1.8MHz resonator
Thank you Josh, this is very useful.
Flavio
On Sat, 1 May 2021 at 12:07, joshbensadon via <joshbensadon= [email protected]> wrote:
The 8250 has a coarse divider for baud rate.?
12 works to divide 1,843,200 to 9600 baud because
1843200 / 12 / 16 = 9600
The next divider number is 13 and to get 9600 at that value you would need...
X / 13 / 16 = 9600
Solve for X = 1,996,800? ?(so 2Mhz would be pretty decent)
2Mhz gives 9615, = 0.2% error
But, as pointed out, 1.8 is available and 1.8432 crystals will also work (adding the loading caps).
On Friday, April 30, 2021, 04:22:10 p.m. EDT, Lee Hart < leeahart@...> wrote:
Zanchius wrote:
> I would be comfortable in flipping a byte or two on the EPROM image, I
> managed to find a programmer that can burn 27256 chips so that also
> wouldn't be an issue.
> May I ask which bytes should be changed?
Hi Flavio,
Download the EPROM source file at
<> from the website at
<>.
In the .ASM or .LST file, search for "LD (ACE_BAUD),A". It occurs in two
places. The first one sets the initial baud rate to 9600 (with a 1.8 MHz
resonator or 1.8432 crystal). Change the byte at 01AE to whatever is
correct for your crystal and desired baud rate.
01A5? 21 80FF??? COLD_START??? LD??? HL,RC_TYPE
01A8? 06 0F??? ??? ??? LD??? B,CS_CLR_LEN
01AA? CD 100C??? ??? ??? CALL??? CLEAR_BLOCK
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_TYPE)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_SOFT)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_STEP)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_CC)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_HALT)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_F0)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_RST0)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_HARD)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RegPtr)
? ? ? ? ? ? ? ??? ??? ??? ;DW??? 0??? ;(ABUSS)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(IoPtr)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RX_ERR_LDRT)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RX_ERR_STOP)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RX_ERR_OVR)
01AD? 3E 0C? ??? ??? ??? LD??? A,12 <=== this sets 9600 baud!
01AF? 32 8FFF? ? ? ? ? ??? ??? LD??? (ACE_BAUD),A
Or, if you're using the Z80-CPU card serial port, you can change the
Z80-SIO card baud rate using this call:
080B? CD CA0D? ? ? ? ? PORT_SPEED??? CALL??? PRINTI??? ???
080E? 0D0A2830 433D3936 ??? ??? DB??? CR,LF,"(0C=9600) BAUD:",EOS
0816? 30302920 42415544
081E? 3A00
0820? 3A 8FFF? ? ? ? ? ??? ??? LD??? A,(ACE_BAUD)
0823? CD F60D? ? ? ? ? ??? ??? CALL??? PUT_BYTE
0826? CD 490D? ? ? ? ? ??? ??? CALL??? SPACE_GET_BYTE
0829? D8? ? ? ? ? ? ? ? ??? ??? RET? C
082A? 32 8FFF? ? ? ? ? ??? ??? LD??? (ACE_BAUD),A
082D? CD F214? ? ? ? ? ??? ??? CALL??? ACE_SET_BAUD
0830? C9? ? ? ? ? ? ? ? ??? ??? RET
Hope this helps!
Lee
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
? ? ? ? -- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377,
--
This email has been checked for viruses by Avast antivirus software.
-- Flavio V. S. Zanchi
flavio@...
"Egal, wie dicht du bist, Goethe war Dichter"
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|
Re: SD I/O 1.8MHz resonator
The 8250 has a coarse divider for baud rate.?
12 works to divide 1,843,200 to 9600 baud because
1843200 / 12 / 16 = 9600
The next divider number is 13 and to get 9600 at that value you would need...
X / 13 / 16 = 9600
Solve for X = 1,996,800? ?(so 2Mhz would be pretty decent)
2Mhz gives 9615, = 0.2% error
But, as pointed out, 1.8 is available and 1.8432 crystals will also work (adding the loading caps).
On Friday, April 30, 2021, 04:22:10 p.m. EDT, Lee Hart <leeahart@...> wrote:
Zanchius wrote:
> I would be comfortable in flipping a byte or two on the EPROM image, I
> managed to find a programmer that can burn 27256 chips so that also
> wouldn't be an issue.
> May I ask which bytes should be changed?
Hi Flavio,
Download the EPROM source file at
<> from the website at
<>.
In the .ASM or .LST file, search for "LD (ACE_BAUD),A". It occurs in two
places. The first one sets the initial baud rate to 9600 (with a 1.8 MHz
resonator or 1.8432 crystal). Change the byte at 01AE to whatever is
correct for your crystal and desired baud rate.
01A5? 21 80FF??? COLD_START??? LD??? HL,RC_TYPE
01A8? 06 0F??? ??? ??? LD??? B,CS_CLR_LEN
01AA? CD 100C??? ??? ??? CALL??? CLEAR_BLOCK
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_TYPE)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_SOFT)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_STEP)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_CC)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_HALT)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_F0)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_RST0)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RC_HARD)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RegPtr)
? ? ? ? ? ? ? ??? ??? ??? ;DW??? 0??? ;(ABUSS)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(IoPtr)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RX_ERR_LDRT)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RX_ERR_STOP)
? ? ? ? ? ? ? ??? ??? ??? ;DB??? 0??? ;(RX_ERR_OVR)
01AD? 3E 0C? ??? ??? ??? LD??? A,12 <=== this sets 9600 baud!
01AF? 32 8FFF? ? ? ? ? ??? ??? LD??? (ACE_BAUD),A
Or, if you're using the Z80-CPU card serial port, you can change the
Z80-SIO card baud rate using this call:
080B? CD CA0D? ? ? ? ? PORT_SPEED??? CALL??? PRINTI??? ???
080E? 0D0A2830 433D3936 ??? ??? DB??? CR,LF,"(0C=9600) BAUD:",EOS
0816? 30302920 42415544
081E? 3A00
0820? 3A 8FFF? ? ? ? ? ??? ??? LD??? A,(ACE_BAUD)
0823? CD F60D? ? ? ? ? ??? ??? CALL??? PUT_BYTE
0826? CD 490D? ? ? ? ? ??? ??? CALL??? SPACE_GET_BYTE
0829? D8? ? ? ? ? ? ? ? ??? ??? RET? C
082A? 32 8FFF? ? ? ? ? ??? ??? LD??? (ACE_BAUD),A
082D? CD F214? ? ? ? ? ??? ??? CALL??? ACE_SET_BAUD
0830? C9? ? ? ? ? ? ? ? ??? ??? RET
Hope this helps!
Lee
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
? ? ? ? -- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
--
This email has been checked for viruses by Avast antivirus software.
|
Re: SD I/O 1.8MHz resonator
No, it is very tight on timing so that it can do full duplex bit bang.? But that runs on the 4Mhz Z80.? The 1.8Mhz is for the UART.
On Friday, April 30, 2021, 11:41:09 a.m. EDT, bill rowe <bill_rowe_ottawa@...> wrote:
Josh: does your serial code do autobaud - i forget? If so it would probably be fine.
Good morning all,
This is proving to be another hard to find component, so I got a 2MHz one instead. If I understood correctly there's a direct correlation with the terminal baud rate provided by the UART. Would 200KHz make much diference?
Cheers
|
Re: SD I/O 1.8MHz resonator
You could cheat and just use the original part:?
You'll probably have to wait a few weeks, however :-{.
|
Re: SD I/O 1.8MHz resonator
You can order direct from Tayda Electronics, and they *are* stocked (3,988,888 parts claimed).
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Lee Hart Sent: Friday, April 30, 2021 12:04 PM To: [email protected]Subject: Re: [Z80MC] SD I/O 1.8MHz resonator Zanchius wrote: Good morning all,
This is proving to be another hard to find component, so I got a 2MHz
one instead. If I understood correctly there's a direct correlation with
the terminal baud rate provided by the UART. Would 200KHz make much
diference? Hi Flavio, Yes, I'm having trouble getting the 1.8 MHz resonators as well. Mouser quit carrying them, so I bought my last batch from Tayda2009 on ebay. But they seem to have gone out of business. As for the FJN3303 and FJN4303 transistors, I have enough for customers; but shipping to the UK is expensive. The frequency is critical to get the right baud rate. Changing from 1.8 to 2.0 MHz will change the baud rate from 9600 to 1066 baud. It will still work if you can set your Terminal program for such an oddball rate. A better solution is to get a 1.8432 MHz crystal, which is a standard frequency and fairly easy to find. Crystals don't have the internal capacitors, so you'll also need to add two 20pf capacitors, one from each side of the crystal to GND (the schematic in the manual shows these capacitors). Another option is to change the divisor in the 8250 UART. This can compensate for your 2 MHz resonator. But it means changing a byte in the EPROM, and burning another one. Lee -- A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away. -- Antoine de Saint Exupery -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com -- This email has been checked for viruses by Avast antivirus software.
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Re: SD I/O 1.8MHz resonator
Lee,
That's brilliant! Thank you for the information.
And thank you everyone for your help as well.
Now the wait for the boards to arrive...
(+_+)
Flavio
Zanchius wrote:
> Humm ... This adds another gremlin in the equation. I'm starting to
> regret ordering only the PCBs.
>
> But hey, there isn't any fun without problems to solve. I may have a
> handful of 1.8432MHz crystal oscillators in my stock so I'll give it a try.
That will work. 1.8432 MHz hits 9600 baud exactly. The 1.80 MHz
resonator is actually 2.4% low (but it works anyway).
Lee
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
? ? ? ? ?-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377,
--
This email has been checked for viruses by Avast antivirus software.
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Re: SD I/O 1.8MHz resonator
Zanchius wrote: Humm ... This adds another gremlin in the equation. I'm starting to regret ordering only the PCBs.
But hey, there isn't any fun without problems to solve. I may have a handful of 1.8432MHz crystal oscillators in my stock so I'll give it a try. That will work. 1.8432 MHz hits 9600 baud exactly. The 1.80 MHz resonator is actually 2.4% low (but it works anyway). Lee -- A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away. -- Antoine de Saint Exupery -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com -- This email has been checked for viruses by Avast antivirus software.
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Re: SD I/O 1.8MHz resonator
Zanchius wrote: I would be comfortable in flipping a byte or two on the EPROM image, I managed to find a programmer that can burn 27256 chips so that also wouldn't be an issue.
May I ask which bytes should be changed? Hi Flavio, Download the EPROM source file at <> from the website at <>. In the .ASM or .LST file, search for "LD (ACE_BAUD),A". It occurs in two places. The first one sets the initial baud rate to 9600 (with a 1.8 MHz resonator or 1.8432 crystal). Change the byte at 01AE to whatever is correct for your crystal and desired baud rate. 01A5 21 80FF COLD_START LD HL,RC_TYPE 01A8 06 0F LD B,CS_CLR_LEN 01AA CD 100C CALL CLEAR_BLOCK ;DB 0 ;(RC_TYPE) ;DB 0 ;(RC_SOFT) ;DB 0 ;(RC_STEP) ;DB 0 ;(RC_CC) ;DB 0 ;(RC_HALT) ;DB 0 ;(RC_F0) ;DB 0 ;(RC_RST0) ;DB 0 ;(RC_HARD) ;DB 0 ;(RegPtr) ;DW 0 ;(ABUSS) ;DB 0 ;(IoPtr) ;DB 0 ;(RX_ERR_LDRT) ;DB 0 ;(RX_ERR_STOP) ;DB 0 ;(RX_ERR_OVR) 01AD 3E 0C LD A,12 <=== this sets 9600 baud! 01AF 32 8FFF LD (ACE_BAUD),A Or, if you're using the Z80-CPU card serial port, you can change the Z80-SIO card baud rate using this call: 080B CD CA0D PORT_SPEED CALL PRINTI 080E 0D0A2830 433D3936 DB CR,LF,"(0C=9600) BAUD:",EOS 0816 30302920 42415544 081E 3A00 0820 3A 8FFF LD A,(ACE_BAUD) 0823 CD F60D CALL PUT_BYTE 0826 CD 490D CALL SPACE_GET_BYTE 0829 D8 RET C 082A 32 8FFF LD (ACE_BAUD),A 082D CD F214 CALL ACE_SET_BAUD 0830 C9 RET Hope this helps! Lee -- A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away. -- Antoine de Saint Exupery -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com -- This email has been checked for viruses by Avast antivirus software.
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Re: SD I/O 1.8MHz resonator
bill rowe wrote: Josh: does your serial code do autobaud - i forget? If so it would probably be fine. No; it doesn't autobaud. But there are two serial ports; one on the Z80-CPU board, and another on the Z80-SIO board. The one on the CPU board uses the 4 MHz resonator; so it will still work. It is fixed at 9600 baud; but would be 4800 baud if you used a 2 MHz resonator, or 19200 if you used 8 MHz etc. The 8250 UART on the Z80-SIO board uses the 1.8 MHz resonator. 18.432 MHz and 3.072 MHz happen to give you all the standard baud rates from 50-38.4Kbaud with negligible error. See the 8250/82C50/16C450 datasheet for details on how to calculate the baud rate constant for various frequencies. Lee -- A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away. -- Antoine de Saint Exupery -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com -- This email has been checked for viruses by Avast antivirus software.
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Re: SD I/O 1.8MHz resonator
Humm ... This adds another gremlin in the equation. I'm starting to regret ordering only the PCBs.
But hey, there isn't any fun without problems to solve. I may have a handful of 1.8432MHz crystal oscillators in my stock so I'll give it a try.
F?
On Fri, 30 Apr 2021, 18:39 Mark Moulding, < mark@...> wrote: A 10% error is really too big, for serial communications.? It miiiight still work, but I strongly doubt it, because by the time you get to the end of the character (10 bits in - start, 8-data, stop), you're a full bit time off.? Most UARTS use an internal clock that's a multiple of the baud rate - typically 16 times - and do their sample for each bit on what should be the middle of the bit (for example, 8 clocks after the one that detected the start bit).? This means that by the end of the character, it's sampling the wrong bit in the serial stream.
I found that errors of less than 3% usually work; I try to keep the timing error to half that or better if at all possible.? Lee's recommendation of a 1.8432 crystal comes in with an error of about 2.4%, which should work fine.
~~
Mark Moulding
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Re: SD I/O 1.8MHz resonator
A 10% error is really too big, for serial communications.? It miiiight still work, but I strongly doubt it, because by the time you get to the end of the character (10 bits in - start, 8-data, stop), you're a full bit time off.? Most UARTS use an internal clock that's a multiple of the baud rate - typically 16 times - and do their sample for each bit on what should be the middle of the bit (for example, 8 clocks after the one that detected the start bit).? This means that by the end of the character, it's sampling the wrong bit in the serial stream.
I found that errors of less than 3% usually work; I try to keep the timing error to half that or better if at all possible.? Lee's recommendation of a 1.8432 crystal comes in with an error of about 2.4%, which should work fine.
~~
Mark Moulding
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Re: SD I/O 1.8MHz resonator
Hi Lee,
I would be comfortable in flipping a byte or two on the EPROM image, I managed to find a programmer that can burn 27256 chips so that also wouldn't be an issue.
May I ask which bytes should be changed?
best
Flavio
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Re: SD I/O 1.8MHz resonator
Zanchius wrote: Good morning all,
This is proving to be another hard to find component, so I got a 2MHz one instead. If I understood correctly there's a direct correlation with the terminal baud rate provided by the UART. Would 200KHz make much diference? Hi Flavio, Yes, I'm having trouble getting the 1.8 MHz resonators as well. Mouser quit carrying them, so I bought my last batch from Tayda2009 on ebay. But they seem to have gone out of business. As for the FJN3303 and FJN4303 transistors, I have enough for customers; but shipping to the UK is expensive. The frequency is critical to get the right baud rate. Changing from 1.8 to 2.0 MHz will change the baud rate from 9600 to 1066 baud. It will still work if you can set your Terminal program for such an oddball rate. A better solution is to get a 1.8432 MHz crystal, which is a standard frequency and fairly easy to find. Crystals don't have the internal capacitors, so you'll also need to add two 20pf capacitors, one from each side of the crystal to GND (the schematic in the manual shows these capacitors). Another option is to change the divisor in the 8250 UART. This can compensate for your 2 MHz resonator. But it means changing a byte in the EPROM, and burning another one. Lee -- A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away. -- Antoine de Saint Exupery -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com -- This email has been checked for viruses by Avast antivirus software.
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Bill in OKC too
Zanchius
Lee Hart