Hi Josh,

Best place is the files section of the group.

While use PCs and program them even the older systems are my thing.
I still have the old don't you wish you have now what DEC had then.
For that I boot the MicroVAX as The OpenVMS Language Senstive Editor
LSE and cross platform systems are still cleaner than some of the current
PCisms.? Linux made than less painful.

The only time I've done SD so far I made FAT file of 256mb on a fresh 1GB
device?so that its allocated sequentially.? Then located the staring Block
number and addressed the blocks in it as LBA starting at xxxxxxH? to the
PC its just a block that's allocated with whatever inside.? The system then
doesn't need to know FAT at all.? The PC only created the larger
container file and allowed me to know the stating address. The CP/M
system populated the container file as sectors starting at xxxxxh.? The
PC was involved but minimally to initialize (create Fat 32 container file)
the disk.

As to BIOS design and storage allocation its not obvious but Alloc is a bit map
that has one bit per addressable block for the current allocation size.? I had to
figure that out in late 1979 when I got CP/M2.2 after running 1.3 and 1.4 in
prior years.? So Alloc map for 8mb using allocation block size of 4K bytes is
256 bytes, allocation block size can be as a large as 16K (32K on clones).
For large disks I use either 4K or 8k allocations.? The Allocation size limits
possible number of files as it sets a minimum granularity.? So for 8mb
using 8K allocation block size limits the disk to 1024 files, for 4K it would
be 2048 assuming DIRectory size can accommodate that.? The size of?
things in the bios for a given disk as all sorts of interactions.? The CP/M
Alteration Guide is rather vague on all that.. Andy Johnson-Larid
CP/M Handbook gets into it and helps make it clearer.

Once up as per earlier CP/M system getfile and putfile tools of my creation
are use to transfer serially via USB serial cable to PCs or real serial (tm)
to other non PC systems usually VAX, PDP-11, or CP/M.

For the BIOS I use on many systems where the device is LBA rather than
track sector I use sectors per track of 4 as the device is typically
512byte sectors and make tracks equal to the size of disk (8MB/512=16384).?
Offset is usually 0000 as I typically boot from Eprom (copy ccp and BDOS
from 8k eprom).? However offset is not part of the size of disk as literal 0th
is the first sector that happens to be directory for X many sectors with
data block after that.

Hard disks are not removable during operating of system so checked entries
will be zero (0) but is used for floppies to insure a media swap is caught before
a write which would trash the directory.

The next high memory cost item is the disk buffers typically equal to sector size or
sometimes block size? I try to keep them small.? For example 512 bytes by 4 drives
can easily eat up 2K of valuable ram in a basic 64K system.? Why?? They cannot
be shared if doing a disk to disk copy havoc would ensue. That's important
as high level languages like C, Pascal, and even assembles want ram to run? fast
and most the minimum is 48K (ram from 100h to base of BIOS) as the BDOS
and CCP are easily overlaid and reloaded.

Sector skew only applies to floppies (rotational delay) and for hard disks and
other modern media CF and SD zero (00) makes more sense.? Save having
skew table or calculating it.? I stopped building in floppies when IDE hit the
streets (as too small and salvage) and drives became cheap.?

CP/M itself has a internal math error that limits it to 8mb.? P2dos, NovaDOS, Zrdos
and a few others fix that at the cost of must be Z80 CPU.? For those 1GB is the limit
and 32Mb partitions makes more sense.? The latter due to the flat file structure.? I've
spent more than a little time inside CP/M (and enhanced clones) as sources have
been available since 1980.

Some of the buffers and other space eaters that the BIOS hides can be burred in
mapped ram such as Z80MC has for the first 32K.? I've used that before in?
a few of my machines where I strive for faster and larger available ram (usually 62K).?

The other trick is if the EPROM is large? as in greater than 16K a bootable image
of CP/M, Bios and a system monitor that will load it to ram. One block or mappable
ram is low ram and others used to support the BIOS.

FYI the z80MC will be paired with a small LCD Display and keyboard as a
portable system on battery.


Allison

Hello all...
She's back!

It been a while and life intervened...? One of the things was getting a Z80MC to play with.
I have over a dozen CP/M systems and a few of my own creation both hardware and
highly modified software. CP/M is a very malleable OS and can support more than
most think or have tried.

So now I have a real Z80MC and the software is done is such a way as to be different
from the BIOS and loaders of my experience.? Back then it was floppy, hard disk,
Eprom based, and of course IDE/CF based,? With that FAT was never a consideration.
I find FAT too tightly tied to PCs and equally as fragile as? CP/M allocation scheme.
The other is that FAT offers a hierarchical file system and CP/M can't/doesn't use it.
It something I'd like to add to CP/M, that is a way to like from one device/Drive
to another (especially on large media).

The other is my system the typical disk is 8MB (or 32mb for ZRDOS) and multiple
partitions.? ?

If all goes well it will be a self development environment for a simpler OS like
NSDos, the goal there is to release it from hardware NS* MDS hard sector disk.

So it will be a playground for experiments started in some case over 45 years ago.

Allison

Bill, not in this version. ? But it could be grown, or another box added to hold it. ?My main purpose was to create a top with buttons, etc. ?The design is in Fusion 360.

Aug

开云体育

That looks great - very functional.? Is there room for a battery?

I have created a case (2 versions). ?I started with Noe Ruiz’s snap box thai i use for everything but the kitchen sink. ?The buttons are made in 2 pieces and glued together. ?The top is used with either the 2 board stack or the 3 board version. ?

Aug
AG5AT

On Fri, Jun 25, 2021 at 02:08 PM, saturn5tony wrote:

When I connected it up years later tho, (that asr33 was owned by my college), to a KIM-1 with its built in teletype drivers I never felt that. Go figure. I did know tho, that the processor It was talking too, was going to change the world.

To those that may not remember this, the KIM-1 was based on the 6502 in the early 70's. What is even more ironic, is that the Apple II that came after, another 6502 machine (one of my favs) was so much more sold to businesses because of the Microsoft Softcard. This really kept the Apple II going into the 80's. So to be honest to this group, the truth and really the creation of what Zilog produced, the Z80, which is in the Softcard, made the 6502 machine so popular. Ironic as this seems even more, these two processors changed the world, really. If you look at the big three in the 70's (in 1977), these two processors was apart of them all as well. What a great time.



So 6502 - 6502 - Z80 ... or.... 6502 - Z80 - Z80? lol

-Tony

On Wed, Jun 23, 2021 at 04:33 PM, saturn5tony wrote:

The mechanics in the asr was amazing as well! I even remember some stories about the guy that designed it too. To me when I hear that sound, I still think of that power.

Yanno, this is true about that power. Not from the teletype tho. It was noisy but it had that particular kind of sound. To me in the early 70's into my teen years, when I heard that connected up to a nearby college via a special modem, I knew it was a computer that the printer was connected too, but that sound gave me the impression of the power of that far away computer, not the asr33.

If I here it it now, I know something very advanced is talking to it.

When I connected it up years later tho, (that asr33 was owned by my college), to a KIM-1 with its built in teletype drivers I never felt that. Go figure. I did know tho, that the processor It was talking too, was going to change the world.

On Thu, Jun 24, 2021 at 01:54 PM, Lee Hart wrote:

A 2-board stack easily fits in the Altoids tin.

Hi Lee,
Oh yea I was lucky, I made that mistake with the sio, so a bit higher, but with the CPU and the keypad (because like Josh with the sio in the middle) I can fit the 2 board stack (cpu/keys) in the tin. Its not really important with the sio tho I think. Having real fun with this design. Thank you guys so much for this very unique design.

Thanks, guys. It's a challenge to design things small; but it also makes it more interesting.:-)

Tony used "low" height IC sockets (-001000). The ones I supply with the kits are "ultra-low" height (-003000). With them (and by removing the plastic body from the headers) you can get it even lower profile. A 2-board stack easily fits in the Altoids tin.

开云体育

On Wed, Jun 23, 2021 at 04:18 PM, joshbensadon wrote:

PS.? You picked some very nice low profile sockets!

Hi Josh!
Those sockets are great. Yea when I made the Keyboard and the CPU I got them correct, but when I reordered the sockets for the SIO I messed up and got the 01000 and the 03000 wrong from Mouser. I was not too upset because its .1 inch higher and I am going to be happy with that.

Not really gonna put it into the Altoids tin. The sio kindof makes that too high as well. I used to repair ASR33 teletypes back in the day, and have worked with a Linotype a small bit when I was in that industry. Yes I know how cool that is. The mechanics in the asr was amazing as well! I even remember some stories about the guy that designed it too. To me when I hear that sound, I still think of that power.

You have to admit this. The front and back view of the Z80MC looks just so cool!

On Sun, Jun 20, 2021 at 07:14 AM, joshbensadon wrote:

I would guess that if ever CP/M could run on a VAX, it would be an emulation.??

Yea I bet your right on that Josh. Man remembering those days was always so cool. We were all on the ground floor of something we new would change the world. I didnt spend that much time on the Vax, was more of a hardware guy at that time but did use it a bit for our development. I do remember how cool the VT100 was and always remember that screen. Cpm or the one that was on the Imsai was so cool as well. When I see it on my Z80 here (or on my AppleII soft-card) it just reminds me of those days.

BTW, love the work you did on the SD card. So having fun with this machine now. Thank you for putting those classics on the B and C drives no less cpm as well.

On Fri, Jun 18, 2021 at 05:23 PM, saturn5tony wrote:

Just got the SD card working today, got C/PM running fine and even kicked up some Zork1 on the second 8-inch (virtual, lolol) drive. Man, its like playing around on the Vax I had back in the 70's hehe!!

Well I have to correct myself again here, lol (man it sucks getting old). I had access to a IMSAI 8080 machine back in 77 and then did some work on a VAX 11/780 machine in late 78. The vax was VMS of course and the Imsai had an s100 Z80 processor board where I did some very brief C/PM on it when I was learning about micro's. The vax (I dont think) ever had C/PM on it unless it was virtual or a special board as well. IDK, I was new to vms as well. Just saying, lol

On Fri, Jun 18, 2021 at 04:28 PM, Lee Hart wrote:

It is possible to get flux in a bad place, like right on the contact area of a connector. But I generally clean my boards with isopropyl alcohol.

Hi Lee,
No problem now. Yes Ive got the classic sn63/37 as well, have been doing this a long time like you. This is one of the orders from mouser I have found that is the problem. I had two shipments of those molex connectors. I looked at my order from them and did a further investigation and I bought about 20 of those molex's 2101's for the few of your kits that I am doing. 6 of these I got from them at the beginning of the year and it had a funny 6 placement holder package, like what you would get from a dealer. All the rest now recently for the 1802 MC I got from mouser in individual bags.

They all look the same until you look close. Its funny because the 6 pack does look odd with its lower tinning but the rest look shiny. Most of those 6 went into the Z80 board and were hard to solder too. Even tho they are soldered in I remembered what they looked like. Thats why I kept using the kester flux on them and made it worse. The rest (now for your MC) solder just fine. Just touch the edge and they wick up just great. LOL!

Maybe it was a re-order that mouser had for them and I was in between for some reason, with the old batch and now the new. Idk.

It wasn't that bad I got it cleared up fast when I figured out what was going on. There clean now and seem to work great on the Z80.? They are really nice and what a great Idea design wise. Cool stuff here Lee. Love the architecture you designed for this, I love it. Just got the SD card working today, got C/PM running fine and even kicked up some Zork1 on the second 8-inch (virtual, lolol) drive. Man, its like playing around on the Vax I had back in the 70's hehe!! Thanks so much for your replies buddy.