Shop OBEX P1 Docs P2 Docs Learn Events
RamBlade: Prop+SRAM+microSD addon to run ZiCog/CPM/PropDos/Catalina, etc — Parallax Forums

RamBlade: Prop+SRAM+microSD addon to run ZiCog/CPM/PropDos/Catalina, etc

Cluso99Cluso99 Posts: 18,069
edited 2022-11-18 05:00 in Propeller 1
RamBlade is a tiny pcb (1.9"x1.2" (48x30.5mm) - fits in a matchbox) and runs CPM2.2 via a soft Z80 emulation.
Programs such as Wordstar, MBasic work (Cobol does not???). It approximates a 4MHz Z80 with 64KB of SRAM, with a small portion dedicated to the EPROM which is loaded from the SD card at runtime.
Two pins provide either a serial connection (eg A USB-seriall TTL pcb or PropPlug - not provided) or Monochrome Video and a PS2 Keyboard connection.


18 Nov 2022 update:
Some links are broken due to forum updates. However there are pics on my (outdated) website here...

I have plenty of bare pcbs, although I would need to order some parts in order to make more. (18 Nov 2022)
Anyone interested should email me cluso -at-
  • RamBlade US$30.00 (subject to change)
  • Shipping: Check with me as local post no longer provides a cheap method
  • microSD card: I email the files and code for you to copy to a FAT32 formatted card.

RamBlade is a double sided SMT pcb designed to run my OS and ZiCog/CPM/PropDos/Catalina/SphinxOS programs using the on-board 512Kx8 SRAM.

(Guess I should state it is essentially the best bits of the TriBlade Prop#2 which we are using for ZiCog)

RamBlade Specifications· (Rev.A)

  • PCB is 1.9"x1.2" (48x30.5mm) SMT (surface mount)
  • Propeller·-·designed for overclocking (104MHz/108MHz/114MHz/120MHz???)
  • SRAM 512Kx8 55nS (optimised for speed - no latches)
  • microSD socket (optional 1GB/2GB/8GB microSD card with ZiCog/CPM2.2 loaded)
  • AT24C512 (64Kx8) EEPROM is fitted which is disabled after boot plus seperate write enable link
  • Designed to run
    • ZiCog & CPM (Z80 emulation)
    • MoCog (6809 emulation)
    • My Prop OS
    • PropDos
    • Catalina C
    • SphinxOS
    • Sphinx compiler (on the RamBlade)
    • other Propeller hosted operating systems requiring external RAM
  • Multipurpose 2x12 0.1" interface connections
    • Designed to plug into·
    • Uses·4·pins·for the interface 3V3,GND,SO,SI
      • 2 to communicate serially to the RamBlade (no resistor protection)
      • 1 each for 3V3 and GND
      • optional onboard 3V3 voltage regulator
    • Uses 4·pins·for optional PropPlug connection for re-programming
      • Alternately can be connected to the·ProtoBoard·to allow·re-programming and/or resetting from the·ProtoBoard
  • Available assembled

General Info (refer to picture above)

  • U1 (prop) and U2 (sram) are on the underside
  • U3·prevents unwanted access to the Eeprom when accessing the sram (shared bus)
  • U4 is AT24C512 Eeprom preloaded with microSD boot code
    • You don't need a PropPlug
  • The xtal pads will take pin sockets for pluggable xtals
    • I am sourcing the pins now (thanks for the supplier info Bill)
    • I am·supplying a 6.5MHz xtal as standard for 104MHz overclocking operation
    • I am hoping to also supply a higher value xtal·for even faster (overclocking) operation
  • The dual row of headers on the RHS are for external connections
    • This connector is NOT fitted as the user will need to identify what connection is required (1x40 pin stakes supplied)
    • 3 = 3V3 (or Vin if using the onboard regulator)
    • G = Gnd (0V)
    • R·· = reset to prop· \\ for external PropPlug connection
    • pI· = program SI ··· ||
    • pO = program SO· · //
    • I· = SI· serial in (two pads)
    • O = SO serial out (two pads)
    • other pads have no connections
    • see diagram below·for·connection details to various boards
  • The microSD card is inserted from the left and is protected by the pcb
  • The WE link is to enable writing to the Eeprom (default unconnected with pullup)
  • The full blue pads are 2mm mounting holes
  • The pads along the top and bottom are uncommitted pads in case you want to add something like a LED/resistor or extra mounting
  • Green dots are just vias like the others (due to my pcb layout program options)
  • VR1 (LM1117T-3.3) and C11 are not supplied/fitted (optional 3V3 regulator)

Connector options


Block Diagram


See this link for my newer RetroBlade2 single chip computer using the Parallax P2 micro

Links to other interesting threads: (mostly broken - try searching for the title)
· Home of the MultiBladeProps: TriBlade,·RamBlade,·SixBlade, website
· Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
· Prop Tools under Development or Completed (Index)
· Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)·
· Prop OS: SphinxOS·, PropDos , PropCmd··· Search the Propeller forums·(uses advanced Google search)
My cruising website is: ··· MultiBlade Props:

Post Edited (Cluso99) : 2/10/2010 8:06:19 AM GMT


Sign In or Register to comment.