Difference between revisions of "Transtape"

Revision as of 17:30, 6 November 2015

A Spanish Hacking Device from HM (Hard Micro, S.A.).

Transtape

Technical

• Uses a 16KB ROM paged into memory at &0000.
• Uses a 8KB static RAM paged into memory at &c000-&dfff and repeats again at &e000-&ffff.
• ROM is paged into the range &0000-&3fff when the red button is pressed and the NMI vector is executed.
• When the black button is pressed, the ROM is paged into the range &0000-&3fff and executes it at &0000.
• This checks the BASIC ROM version, and clears the extra ram if a BASIC ROM from a CPC6128 is found.

Code:

0000 f3        di                               ;; disable maskable interrupts
0001 0100df    ld      bc,0df00h		;; select upper rom 0
0004 ed49      out     (c),c
0006 01817f    ld      bc,7f81h			;; enable upper rom (mode 1 too)
0009 ed49      out     (c),c
000b 31febf    ld      sp,0bffeh                ;; setup stack which is not initialised after reset

000e 3a02c0    ld      a,(0c002h)               ;; read BASIC ROM version number
0011 fe02      cp      02h                      ;; CPC6128?
0013 cc2e0c    call    z,0c2eh		        ;; erase extra RAM

;; this appears to set it up for a reset..
0016 210000    ld      hl,0000h
0019 e5        push    hl			
001a e5        push    hl
001b c30038    jp      3800h                    ;; I think the hardware monitors for address 3800h and if found disables the ROM

• Uses NMI
• Doesn't capture the hardware state like the Multiface does. Code in the ROM reads the hardware state which it restores when resuming the program.
• RAMDIS is asserted when ROM or RAM are active meaning no write through to ram behind.
• Menu code is at offset &3810 and is copied into RAM at &A200.
• Uses port FBF0 (write only)

FBF0 decoding is:
1111 1011 1111 00xx

FBF0 output:
bit 0 is ram enable/disable state
bit 1 is rom enable/disable state
bit 2 is A10 on RAM
bit 3 is A11 on RAM
bit 4 is A12 on RAM
bits 5-7 are not used.

• an opcode read of an address with the following bits:

0011 1xxx xxxx xxxx causes the ram and rom to be disabled. (it jumps to 3800 in the ROM to restore the state)

• Uses port FBFF (input).

bit 7 is used to report lower rom and upper rom enabled state.

Transtape ROM performs a read of 3ffe (lower rom) and fffe (upper rom) and records the state of ROMEN.

Decoding of FBFF is:

1111 1011 1111 11xx

• The same plastic case is used by the Spectrum version of this interface.
• The spectrum version has two switches on the top. One of which chooses load/save. In the Amstrad these holes are filled with plastic caps.

Pictures

• Transtape
• 

  Front

• 

  Back

• 

  PCB Top

• 

  PCB Bottom

• Transtape Layout, thanks to Jose Leandro
• 

  Transtape - PCB Front

• 

  Transtape - PCB Back

• 

  Transtape - Layout

Manual

• Transtape (Micro Hard) Manual

Downloads

• Transtape-ROM.zip (Transtape ROM)
• Transtape (eagle).zip (Transtape files for Eagle)

Links

• http://cpcrulez.fr/hardware-interface_debug-transtape_ASO.htm

• http://hardware.speccy.org/temp/Amstrad-transtape.html