Rertocomputing

Retrochallenge 2017/10

geoRAMThis year our staff decided to enter the retrochallenge competition. Our goal is to reverse engineer the Berkely softworks geoRAM and publish what we discover under the GPL. The geoRAM is a 512KB memory expansion for the Commodore 64 and 128. Unlike the Commodore 1750 REU, which contain a custom chip, the geoRAM is built completely out of standard TTL chips.

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GLINKUSB-LT - User Port RS232 to USB for Commodore 8-bit Computers

glinkusbGLINKUSB-LT is a modern variation of the Commodore VIC-1011. Instead of providing a legacy 12V RS232 connection, it provides a USB Virtual Com Port (VCP) suitable for direct connection to any modern PC. The adapter is fully supported by the standard Commodore BASIC at up to 2400 baud. Jumpers allow the card to be configured as a UP9600 for 9600 baud operation in Novaterm and Striketerm. A reset button is also provided for added convenience.

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F2R16 - Flash based ROM Replacement for Amiga Computers

F2R16The Amiga, like many other computers of the late 80s, uses 16-bit wide mask ROMs to store the machine firmware. Unfortunately, the pinout of these ROMs is incompatible with the JEDEC defined EPROM pinout. Memory manufacturers produced "ROM compatible" EPROMS like the 27C400 to allow development and quick turn manufacturing. These EPROMS are however becoming quite hard to find and still require a UV lamp to erase the chips. F2R16 brings all the benefits of modern flash memory technology to any platform designed to use these obsolete devices.

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MACSIMM - Programmable ROM SIMM for Mac SE/30, IIfx and IIsi

MACSIMMThe Mac SE/30 was the fastest of the classic compact black and white Macintosh computers. It featured a 16MHz 68030 with 68882 FPU and a 32-bit memory interface and supported, albeit not officially, up to 128MB of RAM. Unfortunately the SE/30 ROM contained some old code that used 24-bit addressing making it 32-bit dirty. Many classic computer enthusiasts make their SE/30 32-bit clean by installing a Mac IIsi ROM SIMM. These are nowadays quite rare and difficult to find.

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CGA2RGB - Digital RGBI to analog RGB for Commodore 128 and IBM PC CGA

CGA2RGBThe 80 column output of the Commodore 128 is the same digital RGBI used by the original IBM CGA graphics adapter. Unfortunately nowadays is quite difficult to find a monitor with the suitable RGBI input. The CGA2RGB adapter will convert the TTL RGBI to analog RGB suitable to be connected directly to a 15KHz capable RGB monitor or to the popular Gonbes GBS-8200 VGA converter.

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F2R16-A00 - Flash based ROM Replacement for Amiga Computers

F2R16The Amiga, like many other computers of the late 80s, uses 16-bit wide mask ROMs to store the machine firmware. Unfortunately, the pinout of these ROMs is incompatible with the JEDEC defined EPROM pinout. Memory manufacturers produced "ROM compatible" EPROMS like the 27C400 to allow development and quick turn manufacturing. These EPROMS are however becoming quite hard to find and still require a UV lamp to erase the chips. F2R16 brings all the benefits of modern flash memory technology to any platform designed to use these obsolete devices.

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CGA2RGB-B00 - Digital RGBI to analog RGB for Commodore 128 and IBM PC CGA

A new version of this project is available here

CGA2RGBThe 80 column output of the Commodore 128 is the same digital RGBI used by the original IBM CGA graphics adapter. Unfortunately nowadays is quite difficult to find a monitor with the suitable RGBI input. The CGA2RGB adapter will convert the TTL RGBI to analog RGB suitable to be connected directly to a 15KHz capable RGB monitor or to the popular Gonbes GBS-8200 VGA converter.

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CGA2RGB-A00 - Digital RGBI to analog RGB for Commodore 128 and IBM PC CGA

A new version of this project is available here

CGA2RGBThe 80 column output of the Commodore 128 is the same digital RGBI used by the original IBM CGA graphics adapter. Unfortunately nowadays is quite difficult to find a monitor with the suitable RGBI input. The CGA2RGB adapter will convert the TTL RGBI to analog RGB suitable to be connected directly to a 15KHz capable RGB monitor or to the popular Gonbes GBS-8200 VGA converter.

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