smbaker
Experienced Member
I'm looking for a particular DRAM board for the Heathkit H8. Representative picture from a recent eBay listing is attached. I've seen three listings on eBay that included this card lately, so certainly they're out there in the wild, but circumstances did not align for me to obtain any of them. This is not the Trionyx DRAM board, which is implemented using 74123 timing circuits, but this is an unknown / unbranded third-party board that uses an Intel D8202 DRAM controller. I'm working on my own D8203-based design, and could use a schematic, pictures, or even the card itself if the owner wishes to sell, to use as a reference design. My implementation almost works, not quite. DRAM can be finnicky.
If you're not familiar with H8 memory boards, most of the boards folks see are static memory (SRAM), which is simpler, more reliable, and more resilient to changes in processor speed or timings. There are modern H8 SRAM board designs published on the web using modern ICs and buildable for a nominal cost. DRAM boards are less common, but there was a point in history where the memory size to cost ratio made them popular.
If you're not familiar with H8 memory boards, most of the boards folks see are static memory (SRAM), which is simpler, more reliable, and more resilient to changes in processor speed or timings. There are modern H8 SRAM board designs published on the web using modern ICs and buildable for a nominal cost. DRAM boards are less common, but there was a point in history where the memory size to cost ratio made them popular.