• Please review our updated Terms and Rules here

KAYPRO and KayFreHD as a hard disk module

VERAULT said:
Sorry Shirsch. I beat you to it. I found the rom here: http://planemo.org/retro/advent-turborom/
I burned it and same result! I am really confused. I think Ineed to pull the board and examine the socket. The original rom works but its only a 24 pin rom. Maybe the last few pins have dry sockets or something. I wish someone who has done with can chime in. I feel as if I am missing something.
Click to expand...

Wait, wait, wait... What size is the socket in the motherboard? Are you saying the machine had a 24-pin part in a 28-pin socket? If so, it's certainly possible that the upper address line is not connected - or - possibly the board needs a jumper moved or trace cut. The Advent documentation explains how to add a jumper wire to toggle the top address line appropriately. From your description of the symptoms this is almost certainly the issue.

I put the latest revision of the Kaypro technical manual under the link I sent earlier. Take a very careful stroll through the board layouts and schematic diagrams. There's at least one model with a jumper to choose between 2716 and 2732 on a Kaypro II/4 motherboard. No indication of support for 2764, so you may have to check jumper setting AND do the mod outlined in the TurboROM docs.
 
Last edited:
Here are some photos of the board and socket and area around it. 20200414_140030_resized.jpg Here is the socket. You can see the silkscreen of both size roms on the board under the socket.
This is the area around the socket:20200414_140053_resized.jpg

The only jumpers are these: 20200414_140109_resized.jpg Since they say "A" and "B" I assume they are for floppy settings.
 
VERAULT said:
Here are some photos of the board and socket and area around it. View attachment 60232 Here is the socket. You can see the silkscreen of both size roms on the board under the socket.
This is the area around the socket:View attachment 60233

The only jumpers are these: View attachment 60234 Since they say "A" and "B" I assume they are for floppy settings.
Click to expand...

Have you physically traced the top address line to ensure it's connected to the CPU rather than a pullup or pulldown?
 
I can check, which pins are the address lines on the 2764? And for that matter the z80?


I checked the socket and joints. All good.
 
VERAULT said:
I can check, which pins are the address lines on the 2764? And for that matter the z80?


I checked the socket and joints. All good.
Click to expand...

There are schematics and pictorial board layouts in the service manual I pointed you to. Just identify which board you have and look at the pin numbering on the schematic. Address and data lines are clearly marked.
 
Hi guys. Made some progress. It ocurred to me before I venture down the rabbit hole.... I own 3 working Kaypro 4/84 computers. Why dont I try these roms on another one before driving myself crazy wondering if its my Burning, the eproms, or the computer.

I popped the case on my POS (point of sale, not the other term!) kaypro 4/84 with screen burn in. Since I burned 3 roms I would try them all.
Rom 120200416_101523_resized.jpg
Rom 220200416_101922_resized.jpg
Rom 320200416_101738_resized.jpg

This tells me some very good things. The ROMS are pop-in/plug and play. The machine had no keyboard, adapter, or FreHD when I tested them.. This is how I assumed it would be from the beginning so it is good to know that now.
Since I have two Kayplus roms I will leave one in this machine and first thing I will do with the problem kaypro is replace the socket. The socket works with the original short rom so I will test a new one and report back. But regardless, making progress again!
 
Well I spent a bunch of hours today testing many of the ic's between the system that wont take the kayplus rom and the one that does. Its not an IC issue for sure. I did replace the rom socket btw. I noticed that the boards are not identical even though both came with 24 pin 81-292 revisions of ROM. The system that works with the kayplus rom has a socketed 74ls74 in the U75 position. On the non working board that position is labeled spare and doesn't have a socket (i took the red herring route, added the socket and tried that to no avail).

I really dont know how to progress. The original rom works fine. IT had silkscreen for a 24 and 28 pin eprom. but the 28 pin eproms clearly dont work. there are a few bodges on the bottom of this board which i am sure are factory.
 
Last edited:
VERAULT said:
Well I spent a bunch of hours today testing many of the ic's between the system that wont take the kayplus rom and the one that does. Its not an IC issue for sure. I did replace the rom socket btw. I noticed that the boards are not identical even though both came with 24 pin 81-292 revisions of ROM. The system that works with the kayplus rom has a socketed 74ls74 in the U75 position. On the non working board that position is labeled spare and doesn't have a socket (i took the red herring route, added the socket and tried that to no avail).

I really dont know how to progress. The original rom works fine. IT had silkscreen for a 24 and 28 pin eprom. but the 28 pin eproms clearly dont work. there are a few bodges on the bottom of this board which i am sure are factory.
Click to expand...

Do you have continuity between pin 23 of the EPROM socket and Pin 1 of the Z80? That's address line 11, which is not present on a 2732. In the worst case, why not swap in the motherboard from one of the other units?
 
shirsch said:
Do you have continuity between pin 23 of the EPROM socket and Pin 1 of the Z80? That's address line 11, which is not present on a 2732. In the worst case, why not swap in the motherboard from one of the other units?
Click to expand...

Shirsch yes I do have continuity between pin 23 of the eprom and pin 1 of the z80 (I would imagine the original rom wouldnt work if there wasnt continuity right?)

I mean I could swap it, but Now I want to know what is wrong on this board.
 
VERAULT said:
Shirsch yes I do have continuity between pin 23 of the eprom and pin 1 of the z80 (I would imagine the original rom wouldnt work if there wasnt continuity right?)

I mean I could swap it, but Now I want to know what is wrong on this board.
Click to expand...

Sorry, I goofed: We are interested in A12, not A11. Please check continuity between pin 2 of the EPROM socket and pin 2 of the Z80. You are correct, if A11 hadn't been connected the original ROM would not have worked. Sorry! Typing too quickly and not thinking.
 
shirsch said:
Sorry, I goofed: We are interested in A12, not A11. Please check continuity between pin 2 of the EPROM socket and pin 2 of the Z80. You are correct, if A11 hadn't been connected the original ROM would not have worked. Sorry! Typing too quickly and not thinking.
Click to expand...

Ok just tested. I am getting continuity between pin 2 of z80 and pin 2 of eprom socket (it has the 24 pin eprom in there now so the socket pin is not being used)
 
VERAULT said:
Ok just tested. I am getting continuity between pin 2 of z80 and pin 2 of eprom socket (it has the 24 pin eprom in there now so the socket pin is not being used)
Click to expand...

Ouch. I'm about out of ideas at this point. The fact that you measure continuity on A12 combined with the fact of it working with a 2732 installed indicates that all address and data lines are connected. I suppose there's a chance that the new EPROMs verify in a programmer yet will not operate at system speeds. Although I've never seen such a thing there's always a first time.
 
shirsch said:
Ouch. I'm about out of ideas at this point. The fact that you measure continuity on A12 combined with the fact of it working with a 2732 installed indicates that all address and data lines are connected. I suppose there's a chance that the new EPROMs verify in a programmer yet will not operate at system speeds. Although I've never seen such a thing there's always a first time.
Click to expand...

But the eproms work fine on my other kaypro 4/84. I didnt try them on the 3rd unit because the fact that they work on one shows they shouldnt be the issue. There are some bodges and bridges on the bottom of the board. Possibly they are the reason we cant use anythng beyong the 2732? I can take the board out again and record which ic's and pins are being bridges by the wires perhaps?
 
I think I am going to open a new thread as this isnt the proper place for further troubleshooting that issue. I will continue with you on the freHD image however.
 
For anyone running Z-System (ZSDOS, ZDDOS) on their FreHD equipped Kaypro, here is a compatible clock driver for file timestamping. I could not find any API description for FreHD, so everything was reverse engineered from the Z80 utilities and firmware sources.
 

Attachments

  • frehdrtc.zip
    3.2 KB · Views: 14
Well, I finally got the parts to make the Shim, and as expected, it did not work. I also discovered that Jaq's blog was missing a bit of key information as well as the actual revised GAL file for the Kaypro II (from blog #3). Sigh. I did have a friend see if he could mod the earlier GAL for me, which he did, but things aren't working. When it's hooked up, it acts like either the Eprom or the Z80 chip are missing. Did some testing and without any chips in, I know the z80 is working. No easy way to test the eprom since it's a 28 pin and the old slot was 24 pin, so can't really tell if that's working correctly or not. So yeah, at this point I don't know if it's the hacked GAL, the Eprom, something else. I left Jaq an email on here to see about the missing info/GAL, but he doesn't log in very often. Really doesn't seem like anyone else has done this with the older Kaypro II/83's so there's that as well. :)

Long story short, It's going to be a bit longer before I can get to the frehd testing part. I'm still missing a few parts for that anyway, but I figured i'd at least get this shim part started now.

On the bright side, I did track down the Advent TurboRom for the older Kaypro II series which was not that easy to find (the later turborom's are everywhere though). If anyone is ever looking for that, it's located here as turbo8334.bin (along with the later turnborom and some unique ones like the roadrunner rom):

http://www.retroarchive.org/maslin/roms/

Whether this rom works with the kayfrehd or not, I don't know yet.
 
Is there a final product that can be purchased for the KayFreHD? Next question if I may, which Kaypro models does it work best with? I'm hunting a Kaypro to purchase, and would like to set it up using the KayFreHD as a boot drive. Just want to make sure I get the most compatible version of machine. Thank you.
 
You must log in or register to reply here.
Back
Top