Cumana Disk Controller PCB

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jdavis6809
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Cumana Disk Controller PCB

Post by jdavis6809 » Fri Jan 04, 2019 12:13 pm

Hello,

Cumana pcb built from blank pcb and populated ready for testing

Can anyone tell me if bios rom (attached) is correct only 2k in size not 8k

Also anyone have system disk for cumana controller so I can try with hxc floppy emulator

Also anyone have system disk for microdisc controller so I can try with hxc floppy emulator


Thanks

john davis uk
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Cumana Floppy Controller BIOS.rar
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mikeb
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Re: Cumana Disk Controller PCB

Post by mikeb » Fri Jan 04, 2019 6:30 pm

The Cumana ROM (personally dumped from my own unit) seems to be 8K ...

-r--r--r-- 1 root root 8.0K Oct 6 2010 Data/EPROM Images/OwnedStandard/cumana11.rom

And this dumped from a chip loaned by Steve Marshall ...

-r--r--r-- 1 root root 8.0K Oct 6 2010 Data/EPROM Images/Downloaded/Steve Marshall Loaned Chips/CUMAB01C.rom

So ... have you got a slimmed down light version? :)

Oddly, I have this (from Source: unknown)

-r--r--r-- 1 root root 2.0K Oct 6 2010 Data/EPROM Images/Downloaded/Oric-01/cumana.rom

Which may be what you've found ... ??

My notes indicate that the chip is a 2764 (8K), however the hexdump shows most of the bottom end of the chip is blank.

Real content runs from 0x1800 to 0x1FFF (so that's where your 2K goes, pushed up at the TOP end of the chip).

TL;DR - 6K of blank, 2K of content = 8K.

jdavis6809
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Posts: 73
Joined: Wed Feb 11, 2015 10:39 am
Location: uk

Re: Cumana Disk Controller PCB

Post by jdavis6809 » Sat Jan 05, 2019 1:01 pm

Hello,

I made a rom 8k with 2k at the top I know that jump vector is at top of rom

thanks

john davis uk

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