Difference between revisions of "CPC iRAM"

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[[File:Iram1024.jpg|thumbnail|iRAM/1024 for the CPC 464/664]]
 
[[File:Iram1024.jpg|thumbnail|iRAM/1024 for the CPC 464/664]]
  
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CPC iRAM is a series of open source, DIY friendly, internal RAM expansions for the CPC 6128 and CPC 464/664 (later hopefully also for the Plus/GX4000).
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CPC iRAM is the first [[Standard_Memory_Expansions|standard]] compatible, internal plug & play RAM expansion series for the CPC range of computer and provides up to 1MB of expanded RAM. All variations are open source, DIY friendly and sit in the CPU socket with no further cabling and no additional soldering inside the CPC.  
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The iRAM expansion sits in the CPU socket and requires no additional soldering inside the CPC.  
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== Compatibility ==
 
== Compatibility ==
  
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No incompatibilities have been reported so far.  
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No incompatibilities have been reported so far for the 6128 version.
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The first revision of the 464 version has been found to be incompatible with the [[M4_Board|M4 Board]]. [https://github.com/etomuc/CPC464-iRAM1024/blob/main/README_rev1.md#modification-for-m4-incompatibility A patch has been published].  
  
 
The first 512K of expansion RAM follow the [[Standard_Memory_Expansions#Standard_128K-512K_Expansions_.28dk.27tronics.2Fdobbertin-style.29|DK'Tronics addressing mode standard]], giving up to 576K of RAM to legacy software. More modern software that supports the [[Standard_Memory_Expansions#Extended_1M-4M_Expansions_.28RAM7.2FYarek-style.29|extended 1M-4M standard]] will be able to access all the provided RAM.  
 
The first 512K of expansion RAM follow the [[Standard_Memory_Expansions#Standard_128K-512K_Expansions_.28dk.27tronics.2Fdobbertin-style.29|DK'Tronics addressing mode standard]], giving up to 576K of RAM to legacy software. More modern software that supports the [[Standard_Memory_Expansions#Extended_1M-4M_Expansions_.28RAM7.2FYarek-style.29|extended 1M-4M standard]] will be able to access all the provided RAM.  
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External memory expansions will be ignored once the iRAM is installed. This can be useful for external feature-expansions that also provide a RAM expansion and usually cannot be used in parallel with other (external) RAM expansions. A great use case is to put the ULIFAC in ROM board mode which replaces the full or parts of the ULIFACs RAM with ROM slots. Now with the iRAM installed the CPC still has access to the full RAM provided by the iRAM. If needed a disable switch can optionally be connected to disable the internal iRAM from outside the CPC without removing the iRAM.
 
External memory expansions will be ignored once the iRAM is installed. This can be useful for external feature-expansions that also provide a RAM expansion and usually cannot be used in parallel with other (external) RAM expansions. A great use case is to put the ULIFAC in ROM board mode which replaces the full or parts of the ULIFACs RAM with ROM slots. Now with the iRAM installed the CPC still has access to the full RAM provided by the iRAM. If needed a disable switch can optionally be connected to disable the internal iRAM from outside the CPC without removing the iRAM.
  
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== released ==
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== Available versions ==
  
 
=== CPC 6128 - iRAM/640 ===
 
=== CPC 6128 - iRAM/640 ===
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* 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.
 
* 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.
  
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Status: Released - see https://github.com/etomuc/CPC6128_iRAM-640
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Repository: https://github.com/etomuc/CPC6128_iRAM-640
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''Note: Meanwhile a commercial product is available at Lotharek.pl which also claims to offer 640K and is even smaller, not much larger than the CPU socket itself. However not much information can be found except for the shop.'' 
  
  
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<gallery>
 
<gallery>
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iRAM1088.jpg|iRAM/1088 for CPC 6128
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iRAM1088.jpg|iRAM/1088
 
</gallery>
 
</gallery>
  
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* 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.
 
* 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.
  
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Status: Released - see https://github.com/etomuc/CPC6128_iRAM-1088
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Repository: https://github.com/etomuc/CPC6128_iRAM-1088
  
 
=== CPC 464/664 - iRAM/1024 ===
 
=== CPC 464/664 - iRAM/1024 ===
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* for CPC 464 and 664
 
* for CPC 464 and 664
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* offers two sockets for SRAMs
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* upgrade to 1024K including [http://norecess.cpcscene.net/advancedmemoryusage.html C3 RAM banking] support for 6128 compatibility
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* upgrade to 576K (1 SRAM) or 640K/1024K (2 SRAMS)
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* alternatively without C3 support 576K or 1088K (one or two SRAMs fitted)
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* first SRAM: Upgrade to 576K, following the DK'Tronics standard without support of C3 mode (like many other RAM expansions)
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* second SRAM: upgrade to 1024K (512K SRAM) or optionally also 640K (128K SRAM)
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* [http://norecess.cpcscene.net/advancedmemoryusage.html C3 RAM banking] supported if both SRAMs are fitted
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* easy to assemble, all through-hole components
 
* easy to assemble, all through-hole components
  
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Status: Released - see https://github.com/etomuc/CPC464-iRAM1024
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Repository: https://github.com/etomuc/CPC464-iRAM1024
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== considered ==
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=== PLUS iRAM/1024 ===
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* 1Mb upgrade for Plus series
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* less DIY friendly, probably needs more complex CPLDs (ATF1504)
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Status: very early stage, still considering if it's feasible
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=== GX iRAM/512 ===
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* 512K upgrade for GX4000
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* less DIY friendly, probably needs more complex CPLDs (ATF1504)
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Status: just an idea
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== abandoned ==
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=== CPC 6128 - iRAM/640s ===
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* minified iRAM/640
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* for CPC 6128
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* size just a tiny bit bigger than Z80 CPU socket
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* TSSOP SMD components below Z80
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* requires good soldering skills and special tools to program SMD CPLDs
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Status: fully designed, abandoned as it offers no advantage over DIY friendly version and would only benefit commercial sellers
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(Hint: Lotharek offers a similar expansion commercially for a good price)
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=== CPC 464/664 - iRAM/1024s ===
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* smaller than iRAM/1024, more similar in size to iRAM/640
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* for CPC 464 and 664
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* single 1MB SMD SRAM, upgrade to 1024K
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* [http://norecess.cpcscene.net/advancedmemoryusage.html C3 RAM banking] supported
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* easy to assemble, mostly through-hole components but one SMD SRAM
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Status: working prototype
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=== CPC 6128 - iRAM/576 ===
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* for CPC 6128 only
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* 512K expansion
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* total accessible RAM of 576K in a 6128 (following the DK'Tronics standard)
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* easy to assemble, all through-hole components
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Status: Abandoned in favor of the iRAM/640 which uses the exact same components but offers more total memory.
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=== CPC 464/664 - iRAM/512 ===
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* for CPC 464/664
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* 512K expansion
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* total accessible RAM of 512K in a CPC, following the DK'Tronics standard and support of C3 mode.
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* or 576K without C3 support (512K_C3 / 576K selection per manual switch)
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* easy to assemble,  all through-hole components
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Status: Abandoned as CPC iRAM/1024 will fit into all 464s/664s and is more flexible
 
  
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[[Category:Hardware]] [[Category:Memory expansions]]
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[[Category:Hardware]] [[Category:Memory expansions]] [[Category:DIY| ]]

Latest revision as of 18:38, 5 February 2026

iRAM/640 for the CPC 6128
iRAM/1024 for the CPC 464/664

CPC iRAM is the first standard compatible, internal plug & play RAM expansion series for the CPC range of computer and provides up to 1MB of expanded RAM. All variations are open source, DIY friendly and sit in the CPU socket with no further cabling and no additional soldering inside the CPC.

Compatibility

No incompatibilities have been reported so far for the 6128 version.

The first revision of the 464 version has been found to be incompatible with the M4 Board. A patch has been published.

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.

External memory expansions will be ignored once the iRAM is installed. This can be useful for external feature-expansions that also provide a RAM expansion and usually cannot be used in parallel with other (external) RAM expansions. A great use case is to put the ULIFAC in ROM board mode which replaces the full or parts of the ULIFACs RAM with ROM slots. Now with the iRAM installed the CPC still has access to the full RAM provided by the iRAM. If needed a disable switch can optionally be connected to disable the internal iRAM from outside the CPC without removing the iRAM.

Available versions

CPC 6128 - iRAM/640

  • iRAM/640

  • iRAM/640 built-in

  • RAM Test

  • 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.

Repository: https://github.com/etomuc/CPC6128_iRAM-640

Note: Meanwhile a commercial product is available at Lotharek.pl which also claims to offer 640K and is even smaller, not much larger than the CPU socket itself. However not much information can be found except for the shop.


CPC 6128 - iRAM/1088

  • 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.

Repository: https://github.com/etomuc/CPC6128_iRAM-1088

CPC 464/664 - iRAM/1024

  • iRAM/1024 for CPC 464/664

  • SymbOS on CPC 464

  • for CPC 464 and 664
  • upgrade to 1024K including C3 RAM banking support for 6128 compatibility
  • alternatively without C3 support 576K or 1088K (one or two SRAMs fitted)
  • easy to assemble, all through-hole components

Repository: https://github.com/etomuc/CPC464-iRAM1024

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