TEC-1 The TEC-1 was a single-board "computer" described in Talking Electronics magazine, issues number 10 and 11. Talking Electronics do not have dates on their issues, so the date is uncertain, although 1984 seems a reasonable guess. Talking Electronics operated from Cheltenham, a suburb of Melbourne. The hardware is quite simple, consisting of a Z80 cpu, 2x 8212 8-bit latch, 74C923 keyboard scanner, 20 push-button keys, 6-digit LED display, a speaker, a 2k EPROM and sundry parts. The cpu speed could be adjusted by using a potentiometer, the range being 250 kHz to 2MHz. This is a simple method of adjusting a game's difficulty. Pasting: 0-F : as is + (inc) : ^ - (dec) : V AD : - GO : X Keys: 0 to 9, A to F are on the key of the same name. AD (input an address) is the '-' key. + and - (increment / decrement address) are the up and down-arrow keys. GO (execute program at current address) is the X key. SHIFT - later monitor versions utilised an extra shift button. Hold it down and press another key (use Left Shift). Whenever a program listing mentions RESET, do a Soft Reset. Each key causes a beep to be heard. You may need to press more than once to get it to register. Inbuilt games - press the following sequence of keys: - Welcome: RESET D 1 + 0 2 AD 0 2 7 0 GO GO (Paste: D1^02 -0270XX) - Nim: RESET AD 3 E 0 GO GO (Paste: -3E0XX) - Invaders: RESET AD 3 2 0 GO GO (Paste: -320XX) - Luna Lander: RESET AD 4 9 0 GO GO (Paste: -490XX) Differences between tec1 and tecjmon: On the tec1 a keypress is indicated by an NMI from the 74C923; but on the jmon it sets bit 6 of port 3 low instead. The NMI code is simply a 'retn' in the jmon rom, so we can use the same code. The jmon includes a cassette interface, a serial input connection, and an optional LCD, but the games of the tec1 have been removed.