Sorted by Squirrels.

Friday, 10 June 2016

Feeding the Genie

The einSDein interface is quite versatile. At its connector it is simply a very basic set of Z80 bus and control lines.

RD, WR,IORQ, M1. A[0..7] and D[0..7].

So it shouldn't be hard to interface to other Z80-based computers, right?

Right!



Here is an issue 2 einSDein wired up to a Video Genie, the UK version of the popular TRS-80 clone made by the EACA corporation. It is variously known by other names such as the Dick Smith System 80, PMC-80, TRZ-80 and so on.

The expansion connector breakout was custom made one rainy afternoon, and while it looks a mess it does the business.

A small machine language program was written to perform a directory listing of the SD card. This was converted into a cassette image format, then loaded using PlayCAS.

Here is a video on arguably the best known video distribution channel in the western hemisphere. It shows the aforementioned program pulling a listing from the interface pictured above.

The more eagle-eyed may recognise that the programs on the card are not Genie programs. This is being attended to, dear reader. I have written a converter program which takes cassette image format files and spits out a raw-ish binary dump which can be loaded from SD card. It only works with 'system' or machine language programs at the moment, but a gander at the Level II ROM reference book will soon see to that restriction.

Armed with a copy of MAME and its fine debugger I will spend a few quality hours stepping through the cassette loading functions to see what I need to do in order to craft a work-alike in order to load BASIC from the SD card.

No comments:

This is how we do it

MMC (9) acorn atom (7) zx81 (7) arduino (5) Atari 800 (3) c128 (3) sd card (3) sd2iec (3) sio2sd (3) tatung einstein (3) 6502 (2) Chuckie egg (2) M5 (2) Max6956 (2) QL (2) RCM (2) Sord (2) assembler (2) avr (2) c64 (2) cadsoft eagle (2) eeprom (2) einSDein (2) mmbeeb (2) multi-cart (2) spi (2) system 80 (2) ufat2 (2) vic20 (2) video genie (2) 6502 second processor (1) 6522 (1) 8255 (1) Acorn BBC Micro (1) Apple 2e (1) Apple ][ 2 two (1) BBC 6502 second processor (1) BBC micro (1) DevicePrint (1) Double Choc Chip Muffins (1) FAT (1) IO (1) Jupiter Ace (1) LED (1) Master 128 (1) PCB (1) PIC (1) POV (1) PROGMEM (1) ST (1) Spectrum 128 (1) antex (1) arcade spinner (1) arduino shield (1) atari (1) atmel (1) bakewell tart (1) beer (1) bird's nest (1) bitbucket (1) brokenated XC special (1) cake (1) cassette (1) cassette interface (1) compact flash (1) convert (1) dac (1) de-yellowing (1) eaca (1) efficient (1) einsdein. z80 (1) eye strain (1) failosophy (1) filesystem (1) finally (1) fram (1) french polishing (1) fuse (1) fuses (1) gaming (1) github (1) glue (1) google chrome (1) heroic failure (1) high voltage programming (1) hot irons (1) if (1) jiffydos (1) joey beltram (1) lego robot (1) library (1) lying (1) machine code (1) matron (1) microcode (1) mmc interface (1) mmc2iec (1) mmm (1) mouse guts (1) multicart (1) oscilloscopes (1) pcm (1) pic32mx (1) porn (1) proto shield (1) purple (1) repo (1) retro computer museum (1) retro hard-on (1) rom box (1) sd (1) sd2mmc (1) seadragon (1) silliness (1) small (1) software master (1) soldering (1) sord m5 (1) spi software master (1) stray capacitance (1) string (1) techadventure (1) test equipment porn (1) ts1000 (1) turtle cheesecake (1) tweaking (1) vc20 (1) video head (1) video ram replacement (1) weewee (1) wingasm (1) wire library (1) wodges of IO (1) xilinx cpld (1) yellowing (1) zx spectrum (1) zxpander (1)

About Sir Morris

My photo

Loves: Old computers, Old Techno, Old ladies. Cake.
Hates: New computers.

Unless otherwise stated all of the original work presented here is:

Creative Commons License
Licensed under a Creative Commons Attribution-Noncommercial 2.5 Generic License.

The work of others where referenced will be attributed appropriately. If I've failed to do this please let me know.