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HP-71b card reader eprom module issues
09-07-2020, 02:04 PM
Post: #1
HP-71b card reader eprom module issues
Hi

I decided to buy an eprom module for the HP-71b that is placed in the card reader port. I have burned 2 TI 27c256 emproms but as soon as I try to CAT :port(5) the HP-71b just goes blank until I press cancel. The .bin images were tested in emu71 as IRAMs and worked fine. The burning was also verified as ok. Any thoughts as to why this may be happening ? I guess I could try a different brand of eprom. Is there a special format for writing EPROMs for the HHP eprom module? I note both eprom images are filled with zeros at the end to fill the eprom ?

Any thoughts appreciated

Richard
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09-07-2020, 02:47 PM
Post: #2
RE: HP-71b card reader eprom module issues
(09-07-2020 02:04 PM)coitboy2000 Wrote:  The .bin images were tested in emu71 as IRAMs and worked fine. The burning was also verified as ok. Any thoughts as to why this may be happening ?

Did you complement the bytes from the .bin image to the EPROM for the HHP reader (see here for instance) ?

J-F
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09-07-2020, 09:27 PM (This post was last modified: 09-07-2020 09:34 PM by coitboy2000.)
Post: #3
RE: HP-71b card reader eprom module issues
(09-07-2020 02:47 PM)J-F Garnier Wrote:  
(09-07-2020 02:04 PM)coitboy2000 Wrote:  The .bin images were tested in emu71 as IRAMs and worked fine. The burning was also verified as ok. Any thoughts as to why this may be happening ?

Did you complement the bytes from the .bin image to the EPROM for the HHP reader (see here for instance) ?

J-F

I did see that but was unsure what it means by complemented? Is it just replacing 00s with FFs?

Richard
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09-07-2020, 09:45 PM
Post: #4
RE: HP-71b card reader eprom module issues
(09-07-2020 09:27 PM)coitboy2000 Wrote:  I did see that but was unsure what it means by complemented? Is it just replacing 00s with FFs?

Richard

Invert all the bits. Change the 1's to 0's and 0's to 1's. It's needed for the 71 to read this format EPROM chip in the HHP carrier.

--Bob Prosperi
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