CPC iRAM

CPC iRAM is a series of open source, DIY friendly, internal RAM expansions for the CPC 6128 (later hopefully also for the 464 and 664).

The iRAM expansion sits in the CPU socket and requires no additional soldering inside the CPC.

The first 512K of expansion RAM follow the DK'Tronics addressing mode standard, giving up to 576K of RAM to legacy software. More modern software that supports the extended 1M-4M standard will be able to access all the provided RAM.

released

CPC iRAM/640

• for CPC 6128 only
• 512K expansion
• total accessible RAM of 640K in a 6128 (64K Base RAM + 512K RAM expansion + 64K secondary RAM bank of the 6128)
• easy to assemble, all through-hole components
• perfectly fits into a CPC 6128, even with socketed ROM or RAM. In Schneider CPC 6128 the metal shielding needs to be removed or altered.

Status: Released - see https://github.com/etomuc/CPC6128_iRAM-640

currently in development

CPC iRAM/1088

• for CPC 6128 only
• 1024K expansion
• total accessible RAM of 1088K in a 6128 (64K Base RAM + 1024K RAM expansion)
• easy to assemble, but SRAMs are in SMD packaging (SOP32) due to size constraints in the CPC 6128
• perfectly fits into a CPC 6128, even with socketed ROM or RAM. In Schneider CPC 6128 the metal shielding needs to be removed or altered.

Status: Finished, will be released in late 2025

CPC iRAM/1024

• for CPC 464 and 664
• offers two sockets for SRAMs
• upgrade to 576K (1 SRAM) or 640K/1024K (2 SRAMS)
• first SRAM: Upgrade to 576K, following the DK'Tronics standard without support of C3 mode (like many other RAM expansions)
• second SRAM: upgrade to 1024K (512K SRAM) or optionally also 640K (128K SRAM)
• C3 RAM banking supported if both SRAMs are fitted
• easy to assemble, all through-hole components

Status: working, currently testing, maybe needs another PCB revision

CPC iRAM/1024s

• much smaller than iRAM/1024, more similar in size to iRAM/640
• for CPC 464 and 664
• single 1MB SMD SRAM, upgrade to 1024K
• C3 RAM banking supported
• easy to assemble, mostly through-hole components but one SMD SRAM

Status: prototype assembled, not tested yet

considered

PLUS iRAM/1024

• 1Mb upgrade for Plus series
• less DIY friendly, probably needs more complex CPLDs (ATF150x)

Status: very early stage, still considering if it's feasible

GX iRAM/512

• 512K upgrade for GX4000
• less DIY friendly, probably needs more complex CPLDs (ATF150x)

Status: just an idea

abandoned

CPC iRAM/576

• for CPC 6128 only
• 512K expansion
• total accessible RAM of 576K in a 6128 (following the DK'Tronics standard)
• easy to assemble, all through-hole components

Status: Abandoned in favor of the iRAM/640 which uses the exact same components but offers more total memory.

CPC iRAM/512

• for CPC 464/664
• 512K expansion
• total accessible RAM of 512K in a CPC, following the DK'Tronics standard and support of C3 mode.
• or 576K without C3 support (512K_C3 / 576K selection per manual switch)
• easy to assemble, all through-hole components

Status: Abandoned as CPC iRAM/1024 will fit into all 464s/664s and is more flexible