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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment. |
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Thread Tools |
8th Nov 2022, 11:36 pm | #21 |
Triode
Join Date: Nov 2022
Location: Croydon, Surrey, UK
Posts: 37
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Re: DM8678 replacement
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11th Nov 2022, 10:09 am | #22 | |
Hexode
Join Date: Jan 2021
Location: Ashford, Kent, UK
Posts: 318
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Re: DM8678 replacement
Quote:
Here are the font tables in an asm listing |
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11th Nov 2022, 6:52 pm | #23 |
Hexode
Join Date: Jan 2021
Location: Ashford, Kent, UK
Posts: 318
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Re: DM8678 replacement
The Tech Notes for the RealView VDU card and DM8678 Emulator modules are available here. It's aimed at giving enough info to understand the operation of the cards and perhaps make modifications (at your own risk ). It's not a resistor-by-resistor description, but if you need any clarifications then let me know.
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13th Nov 2022, 7:48 pm | #24 |
Hexode
Join Date: Jan 2021
Location: Ashford, Kent, UK
Posts: 318
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Re: DM8678 replacement
The closest reference I found was CRH, but no description of what font that has. I wonder if it is a custom font? Nat Semi DM8678 data sheet describes how to submit a font on punched cards. Have you been able to test the device?
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13th Nov 2022, 8:57 pm | #25 | |
Octode
Join Date: Mar 2020
Location: Kitchener, Ontario, Canada
Posts: 1,294
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Re: DM8678 replacement
Quote:
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16th Nov 2022, 10:47 pm | #26 |
Hexode
Join Date: Jan 2021
Location: Ashford, Kent, UK
Posts: 318
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Re: DM8678 replacement
From what I’ve read the Microtan had sockets for both the BWF upper case and CAE lower case character generators. I don’t suppose the silk screen on the CRC version you have is poorly printed and it’s actually CAE?
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16th Nov 2022, 11:29 pm | #27 |
Octode
Join Date: Mar 2020
Location: Kitchener, Ontario, Canada
Posts: 1,294
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Re: DM8678 replacement
Yes the microtan has two sockets for character generators, mine has both sockets fitted but I only had the upper case generator. The CRC might be a lower case variant, I guess I won’t know until I try it. I’d prefer not to do a wire mod to use the 86S128, though I have another main board that I might mod. The other board is not in good condition, all ICs were in sockets but most have been robbed, it was also modded to fit 4k ram as a stack of 2114s and is coated in brown dust that I suspect is from cleaning rust off a car in the garage. The best of the two boards has amost all ICs soldered to the board, I keep putting off trying to apply power to see if it still works.
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26th Nov 2022, 11:37 am | #28 |
Diode
Join Date: Nov 2022
Location: Waterlooville, Hampshire, UK
Posts: 4
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Re: DM8678 replacement
According to their datasheet (www.microtan.ukpc.net/Datasheets/DM8678.pdf) National Semiconductors didn't make a DM8678 CRC variant.
If looking for replacements for the Microtan, a piggy-back module has been developed here: http://microtan.thegrahamfamily.me.u...r-replacement/ |
27th Nov 2022, 6:04 pm | #29 | |
Octode
Join Date: May 2018
Location: Northampton, Northamptonshire, UK.
Posts: 1,440
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Re: DM8678 replacement
Quote:
DMB67B Char Gen ....... . . £15.20 (both CAB & BWF avail.) - See attached page extract / the full magazine can be found at: https://worldradiohistory.com/UK/Per...No.1-S-OCR.pdf Rather expensive (even before 8%? VAT back then), and I wonder how much NS blank PROM's were around that time, being as they gave you the contents to generate your own Character PROM's. |
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28th Nov 2022, 5:46 pm | #30 | |
Triode
Join Date: Nov 2022
Location: Croydon, Surrey, UK
Posts: 37
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Re: DM8678 replacement
Quote:
Attached the corrected binary. |
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2nd Dec 2022, 10:45 pm | #31 |
Hexode
Join Date: Jan 2021
Location: Ashford, Kent, UK
Posts: 318
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Re: DM8678 replacement
Thanks for posting the corrected font table. I had noticed the 3 was incorrect but not the others.
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18th Mar 2023, 2:31 pm | #32 |
Hexode
Join Date: Jan 2021
Location: Ashford, Kent, UK
Posts: 318
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Re: DM8678 replacement
I've created a custom font set for the MK14 Invaders game and loaded it to the DM8678 Character Generator emulator module. There's a 2 minute video here:
https://youtu.be/UZ5LpBQ0O3A |
19th Mar 2023, 12:11 pm | #33 |
Octode
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 1,363
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Re: DM8678 replacement
I watched that video last night - looks amazing and it reminded me so much of the custom font board that came out for the ZX81 cant remember by who but, I did drool over it.
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