Introduction

[ivan.beccaro]

Hi all, i'm a new (soon physically, still has to be delivered) owner of a cromemco c10 system, and possibly in the future of some s100 model (or replica at least)

Obviously i'm a retrocomputing enthusiast, last acquisition was a fully working NCR Decision Mate V in echange for a Sun Enterprise server.

Since i don't know the actual conditions of the C10 soon to be delivered (it should be at least partially working) i'll probably be soon in need of some assistance to fix it (afaik at least the 5,25" fdd is untested)

Meanwhile thanks for the add.

[Peter Higgins]

For a start, take a look at this discussion titled "C-10 Restoration":

https://groups.google.com/g/cromemco/c/LBwXsmry3GA/m/NAoRN4hTBAAJ

[ivan.beccaro]

the person who sold it said he repaired the psu, and it powers on and shows a cursor but he did not test it further due to lack of keyboard cable (i got a RJ9 cable for the purpose), so my first question, since i never saw it turning on is:

When the C10 powers on does it try to boot from disk or has it some kind of monitor in rom wich show actually "a cursor"?

[Peter Higgins]

At power-up, the C10 boots into the CROS (ROM-based) monitor. It is necessary to have they keyboard connected for the C10 to boot into CROS - without a keyboard the C10 just displays a blank screen. A photo of what the CROS startup screen looks like can be found in the discussion I provided a link to (above).

[ivan.beccaro]

thank you! this is a foundamental info for me (not having ever seen a c10 working)

[ivan.beccaro]

now i have a bit of info on the symptoms on the c10 i'm going to purchase (get in exchange for another machine actually). The owner said that he repaired the psu and was able to get a cursor on the screen, he said i treied with a keyboard from another working c10 and was able to gett a pair of beeps from the machine but still there's only the cursor, pressing some keys the cursor despair for a moment and then it comes back. he said also that the orginal rom was replaced by an eprom but trying with the rom from the working c10 nothing changed. Now that i have access to the repo docs i'll take a look deeper in process of the c10 start to try to approximate some kind of potential diagnose and understand if i may will be able to fix. But meanwhile i leave this annotation here for tips and suggestions, thank you in advance

[ivan.beccaro]

adding a further note, the behaviour on pressing a key look like the keyboard is someway detected and working so the problem wich blocks CROS from going further it seems to be elsewhere (not aware of how the process takes place, but i believe before testing memory it should print the keyboard detection message)

[Chris LaFond]

Do you have a floppy drive and boot floppy hooked to the computer?

The C10 CROS will also go into terminal mode if a serial connection is detected. maybe try hooking the serial port up to another terminal (like a linux box) and see if you can get output. Read up on sections B through D of the C-10 User Manual.

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[ivan.beccaro]

i'll surely try the connection to a linux box (null modem cable i presume) asap, about the drive no floppy is stuck in the drive, i need confirmationa and possibly a list of the sequential beeps produced form the C10 during poweron sequence. I found no info inside the technical manual, thanks for the tip and for the upcoming ones

[Chris LaFond]

Ivan:

My C-10 with a keyboard plugged in and no floppy drives: from power button flipped its about a second and then there is 1 short beep from the keyboard and then takes about 10 seconds for the screen to warm up and I see the message:

Keyboard: USA1, version 07

Cromemco CROS, version 1.05

hope this helps

To view this discussion visit https://groups.google.com/d/msgid/cromemco/724a137b-ae9c-4023-b816-56def188e0c0n%40googlegroups.com.

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[ivan.beccaro]

surely it helps, at least i know the first single beep if alone is from the keyboard (with was mentioned in the tech manual also but i had no specifications of a possible tests order),  thank you, now i'm asking myself what's the second beeps.
:)

i hooe i'll be able to understand more since i greedy want this machine :)

[ivan.beccaro]

here it is, taken it home despite all, gave a working msx2 in exchange and i still do not know if i will be able to fix it

[KDK KDK]

Ivan:

Let me know if you need a boot disk I can send you one if needed

To view this discussion visit https://groups.google.com/d/msgid/cromemco/5921aa72-c5ae-498e-9e40-4a4984f954edn%40googlegroups.com.

[ivan.beccaro]

thank you Chris, first i have to test it, i will post detailed symptoms here, then i'll try to teledisk one of the images i found, possibly if i'll be not able to i'll ask you. Forn now i ned a rj9 4p4p cable for the keyboard and then will be able to post a deeper description of the problems it gave (i gave a working  philips nms8220 msx 2 in echange for this not/partially working machine :) so i MUST fix it)

[ivan.beccaro]

hi again, 1st power on today, in the photo you can see the result, the cursor starts from the upper left corner of the screen and keep scrolling down (the person who gave it to me said when it powered it on the cursor remained fixed in the upper left corner flashing, no scroll). I used an old phone receiver cable for connecting kbd (rj9 4p4c, should be straight not crossed). Any idea on how to proceed? The dude who gave it to me suggested it maybe a corrupted rom/eprom.

In the attached clip you have a better view of the beahaviour. Thanks in advance to all.

[KDK KDK]

Looks like the video circuit is having problems.  Did the keyboard beep? If you hook up a floppy drive does it try to boot?

To view this discussion visit https://groups.google.com/d/msgid/cromemco/43453a21-282a-4625-af88-70b097556965n%40googlegroups.com.

[ivan.beccaro]

the keyboard beeps only on keypress, still not connected the floppy, i'll try tomorrow and report here the results

[KDK KDK]

The keyboard has a setting to beep every keystroke if you want. With the way the screen is acting and no beep on power tells me it is not booting. The video signal only works if the CPU is sending commands to the video chip. 

Looking into the Intel p8275 video controller. It won't raster if nothing is sending it commands. Could be a power supply issue. Check voltages. I also believe these machines have a few RIFA caps that will need to be replaced

To view this discussion visit https://groups.google.com/d/msgid/cromemco/f0cbd3a5-d0ba-44cf-873e-1417faf77ac4n%40googlegroups.com.

[ivan.beccaro]

i'll check voltage asap, about the RIFA the person givint the cl10 to me said he replaced them and repaired the psu. I'll check anyway. I'll check the video controller also, thanks Chris

[ivan.beccaro]

i confirm the behaviour is the same with the keyboard disconnected, il proceed to open the case and check signals and voltages and the rom