Finally got mu H8 System working!

[John Delano]

I finally have my H8 system working! Thanks to Joe Travis for all the help! You probably reduced the repairs by several weeks!

The H9 was the hardest repair due to poor contacts and a bad PROM (Thanks Dave McGuire for burning a replacement for me!). During this I also learned that the PROM tables in the H9 manual are not 100% correct. Anyone needing replacement PROMs, be sure to get one programmed using an image from a known good one. Especially the 444-10. If you use the table from the manual, the cursor will advance until you press [Home], and you won't be able to use the H9!

Thanks to everyone in the Heathkit community. I found many documents online to help diagnose different problems and build needed cables.

[norberto.collado koyado.com]

Very nice and congratulations in getting such system up and running. I like your cassette player. 😊

 

Norberto

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[John Delano]

Norberto,

That 's an Interact Model 1 computer. The cassette player is built-in.

[norberto.collado koyado.com]

That is cool!

 

I will be posting the H9 PROM binaries on my website hopefully tomorrow. They are an exact image of the original H9’s ROM’s. That should help in making exact copies as needed.

To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/5575ed02-6d3d-4498-84d3-8c241904ca23n%40googlegroups.com.

[John Delano]

That's awesome. 

[Dave McGuire]

On 5/21/22 09:54, John Delano wrote:
> I finally have my H8 system working! Thanks to Joe Travis for all the
> help! You probably reduced the repairs by several weeks!
> The H9 was the hardest repair due to poor contacts and a bad PROM
> (Thanks Dave McGuire for burning a replacement for me!). During this I
> also learned that the PROM tables in the H9 manual are not 100% correct.
> Anyone needing replacement PROMs, be sure to get one programmed using an
> image from a known good one. Especially the 444-10. If you use the table
> from the manual, the cursor will advance until you press [Home], and you
> won't be able to use the H9!

Wait, what? This is most distressing. Are you able to determine the
differences?

I replaced the 444-10 with a PROM that I programmed from the manual.
I can't easily get to it at the moment but I'm pretty sure it worked fine.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

[Dave McGuire]

On 5/21/22 17:08, norberto.collado koyado.com wrote:
> I will be posting the H9 PROM binaries on my website hopefully tomorrow.
> They are an exact image of the original H9’s ROM’s. That should help in
> making exact copies as needed.

Please send out a link when you do. I'm very curious about the
differences.

[Mark Garlanger]

Each of the manuals went through several revisions. Maybe an earlier one had an error that was fixed. I have at least revisions 595-2017-02 and 595-2017-03 for the H9 Operation manuals.

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[norberto.collado koyado.com]

Just one byte off for 444-10 PROM.

 

Original files here:

 

http://koyado.com/heathkit/New-H8-Website/download/h9-proms.zip

 

 

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[Joseph Travis]

Does this type of PROM "burn" 1's?  If so, it may be possible to re-burn any PROMs with the correct value.

Regards,

Joe Travis n6ypc

To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/BE6F3AE1-4910-4599-9FF2-ED15172EF528%40koyado.com.

[John Delano]

If I remember it was off by only 1 bit. I would need to pull the chips and compare them to find all the differences. 

[Dave McGuire]

On 5/22/22 08:26, Joseph Travis wrote:
> Does this type of PROM "burn" 1's?  If so, it may be possible to re-burn
> any PROMs with the correct value.

Yes, these are "blank 0/write 1" PROMs, and they do support
single-byte writes.

[John Delano]

The 444-11 and 444-12 both work with the table data, but I remember there were some differences in the 444-12, but the H9 is working with those PROMs. The few bits may cause some odd glitches, though. My 444-11 was completely dead so I couldn't compare it to the tables.