#182

I've collected and build CP/M systems for decades (over 4)
so I have system that run from sludge slow to current idea of fast.
Z80s at 10mhz, Z180s at 12mhz and A Z280 at 10mhz.
That and no shortage of S100, Multibus, and SBC systems
to run.

Biggest bottleneck is mass storage IO, 5.25 floppy generally
is slow, many hard disks were not fast.? ?Of all CF is usually
fastest (best if 8bit mode) and SD slower as the SD has
more protocol overhead and the serializing if not done in
hardware is slow.? Of course there are implementation
dependencies but the faster?systems usually farm out
the disk/storage IO to a slave cpu in some form.??

Speed is good if it can be had simply.? A Z80 running at? 6, 8
or 10mhz can be simple.?

All that said why speed is nice to have, I use multiplan, Dbase,
smallC, BDS-C, Pascal and a lot of other software like Vedit
and speed helps.

Allison

#181

开云体育

and 4mhz should be enough for anyone ?

Show quoted text

From: [email protected] <[email protected]> on behalf of ajparent1/kb1gmx <kb1gmx@...>
Sent: September 29, 2020 12:35 PM
To: [email protected] <[email protected]>
Subject: Re: [Z80MC] Where's the CPM files

?

Considering the DEC Robin ( I have two) is a 4mhz Z80 with 64K of ram?
with banked boot/terminal roms and slow floppies (TM100s) is the
comparison?that's terrible.

A long time back I got a dozen of the Z80 board used to make up
the Robin, They are 4mhz Z80, 64k of Dram, two 24 pin eprom
sockets (2732), FDC and 4 serial ports, basis for a good system.

So I took one and put on revised roms and it uses a CF
interfaced to the old FDC? socket (no floppies) and its
fast ss any 4mhz Z80.??

Having multiple real systems to compare at 4mhz is nice:

Allison

#180

Considering the DEC Robin ( I have two) is a 4mhz Z80 with 64K of ram?
with banked boot/terminal roms and slow floppies (TM100s) is the
comparison?that's terrible.

A long time back I got a dozen of the Z80 board used to make up
the Robin, They are 4mhz Z80, 64k of Dram, two 24 pin eprom
sockets (2732), FDC and 4 serial ports, basis for a good system.

So I took one and put on revised roms and it uses a CF
interfaced to the old FDC? socket (no floppies) and its
fast ss any 4mhz Z80.??

Having multiple real systems to compare at 4mhz is nice:

Allison

#179

开云体育

I used reverse connectors as well for the olduino/z.? Are you able to put the front panel on top of the SIO?

The Olduino is a retro-Arduino. This one uses a Zilog Z80 processor from the 1970s but adds hardware and software so it can function like an arduino and use some arduino add-on shields. The Olduino/Z is more limited than an Arduino but that is part of the fun. The Olduino/Z has 8 dedicated output pins and 7 inputs…

olduino.wordpress.com

Show quoted text

From: [email protected] <[email protected]> on behalf of Paul Bigwood <paul@...>
Sent: September 28, 2020 11:05 AM
To: [email protected] <[email protected]>
Subject: Re: [Z80MC] Where's the CPM files

?

Thanks all,

Working fine now. I downloaded the CPM files from the website and simply copied the contents of the ZIP to the SDcard and then booted the Z80MC with the SIO board but not the FP. Some activity and? then hey presto CPM prompt.?

Works fine. Bit slower than I recall my old DEC Robin, but fine. Will have some fun putting Small C and Pascal on to the card.?

I've got plans for a Z80 PIO and CTC on my expansion board.

Meant to mention that I reversed the pins and sockets on the boards, so that I could plug directly into the CPU board with single core bare wires or male pin back to back breadboard wires, rather than having to use DIP sockets. I also found some 20 way versions of the white connectors from EBay and used those with one 10 way supplied to make the inter board connectors.?

Here's a photo of the completed boards.

Best Regards

Pau l

#178

Thanks all,

Working fine now. I downloaded the CPM files from the website and simply copied the contents of the ZIP to the SDcard and then booted the Z80MC with the SIO board but not the FP. Some activity and? then hey presto CPM prompt.?

Works fine. Bit slower than I recall my old DEC Robin, but fine. Will have some fun putting Small C and Pascal on to the card.?

I've got plans for a Z80 PIO and CTC on my expansion board.

Meant to mention that I reversed the pins and sockets on the boards, so that I could plug directly into the CPU board with single core bare wires or male pin back to back breadboard wires, rather than having to use DIP sockets. I also found some 20 way versions of the white connectors from EBay and used those with one 10 way supplied to make the inter board connectors.?

Here's a photo of the completed boards.

Best Regards

Pau l

Z80MC_SIO_CPU_FPB-small.jpg

#177

>>So, there is a chance that writes don't make it to disk, but since most
normal programs in CP/M return to CP/M, the reading of the system
sectors should satisfy clearing out the cache.<<

CP/M bios get signals from the BDOS to determine that for deblocking.
The BIOS then only needs to do a "updated" read and the SD will write
its cache and get the requested block.

Warm-boot should do that as well and Cold-boot should as well as the
first thing is a read to login the current directory (usually A:).

That should apply both for CP/M deblocking and triggering a dirty
cache in the SD (its internal caching).

Allison

#176

Hi Alison,

The way I wrote CP/M BIOS on the Z80MC is to open a FAT16 File and use it like a drive.

I wanted to use the SD card in a manner that would still let the user read/write files through existing Windows file explorer.

I thought about just mapping sectors directly to CP/M but that's far too easy, wasteful and not my style.

In CP/M, access to a block is translated to 128 byte disk sectors.

The BIOS converts this to a 512 byte sector, and the cluster required, then goes FAT hopping.

The 512 byte sector is read into RAM and a pointer to the correct 128 bytes is returned.

Of course, I consider the 4 (128 sectors) as cached and new SD card reads are not required.

Writing updates the cache and simply flags a "dirty data" condition.? The next read that changes the 512 byte cache will trigger the write back to disk.

So, there is a chance that writes don't make it to disk, but since most normal programs in CP/M return to CP/M, the reading of the system sectors should satisfy clearing out the cache.

Cheers,
Josh

On Saturday, September 26, 2020, 01:57:34 p.m. EDT, ajparent1/kb1gmx <kb1gmx@...> wrote:

With care cpm explorer runs in wine.

Either case CP/M knows nothing of fat so what many do is create a
contiguous 8mb file as a container file and then find out what block
address it starts at.? Then CP/M addresses the block directly
without fat.

So CP/M will not read fat files, the file structure is very incompatible.
Its possible to run a utility that does BIOS direct DISK IO and read
FAT using a program that knows fat structure but that's only useful
to get from CP/M to FAT or FAT to CP/M.? I have that for AmproLB+
and Kaypro4/84 its called DOS.? Obvious the media must be compatible
(720K 3.5" floppy was the standard here for that) as back then SD and CF
were far in the future.? The program called DOS is on the SC CD but it
would need a great amount of work for FAT devices larger than 500mb.

SD cards do not care what file format you use.? ?If you partition it you
can have multiple CP/M partitions.? Oh CP/M does not use partition
table on that media either.? ? Use a freshly formated or new SD
(1gb is plenty large) and write a bunch of FAT files of 8MB each then use?
a program to get the starting bock address of each.? The CP/M BIOS
needs to know [when you code it, or as a default that can be changed
for B:/C:/D:... drives] what the block starting address is for a given Logical Drive.

Using linux DD is both your friend and feind.? It can write blocks to specified
addresses easily but only using great care as it can write blocks to specified?
addresses easily (oops wrong blocks or device).

Allison

#175

With care cpm explorer runs in wine.

Either case CP/M knows nothing of fat so what many do is create a
contiguous 8mb file as a container file and then find out what block
address it starts at.? Then CP/M addresses the block directly
without fat.

So CP/M will not read fat files, the file structure is very incompatible.
Its possible to run a utility that does BIOS direct DISK IO and read
FAT using a program that knows fat structure but that's only useful
to get from CP/M to FAT or FAT to CP/M.? I have that for AmproLB+
and Kaypro4/84 its called DOS.? Obvious the media must be compatible
(720K 3.5" floppy was the standard here for that) as back then SD and CF
were far in the future.? The program called DOS is on the SC CD but it
would need a great amount of work for FAT devices larger than 500mb.

SD cards do not care what file format you use.? ?If you partition it you
can have multiple CP/M partitions.? Oh CP/M does not use partition
table on that media either.? ? Use a freshly formated or new SD
(1gb is plenty large) and write a bunch of FAT files of 8MB each then use?
a program to get the starting bock address of each.? The CP/M BIOS
needs to know [when you code it, or as a default that can be changed
for B:/C:/D:... drives] what the block starting address is for a given Logical Drive.

Using linux DD is both your friend and feind.? It can write blocks to specified
addresses easily but only using great care as it can write blocks to specified?
addresses easily (oops wrong blocks or device).

Allison

#174

Paul Bigwood wrote:
I've finally finished my SIO Card - long story!, and it seems to be
working fine, but I can't boot CPM.
I'm pretty sure the SD Card I have used (SanDisk 2GB Black) is the one
supplied with the kit.
Checking it on my W10 PC shows no files but around 100K of data used?
Booting the Z80MC and typing S shows a sub menu L and W. L prompts the
same sub menu and W and prompts to enter a file name? Entering a file
name like TEST.TXT just comes back with a ?. Have I overwritten the
system somehow?

I haven't been able to find any instructions on line. Is there a FAQ I
should be looking at? Can I download the files from somewhere?Hi Paul,

I format the SD-card in FAT16; but do not pre-load the CP/M files onto it. The computer I'm using is running linux, and it's problematic to load the CP/M files on it because Josh's CP/M explorer is Windows. (I have to get another computer with a working Windows setup to do it).

If you look on my website, you'll find the files to load, and the CP/M explorer program to do it. Once you get them loaded, you should be all set!

Once CP/M is on the Z80MC, then it has the XMODEM program and can transfer any files or disk images with any PC "terminal" program that supports XMODEM.

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