Hi Tony Well I got a good response to my musings re British Computers. I'm busy cutting and pasting all of the data to give me a list of who said what and who has what. A passing thought.. should there be a British Section at Bletchley? Rod -----Original Message----- From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org] On Behalf Of Tony Duell Sent: 31 August 2007 23:35 To: cctalk at classiccmp.org Subject: Re: British Computers. Yes. The Dragon 32 was based on the same Motorola Application Note (for the 6883) as the Tandy Color Computer, anf is a very similar machine. Although for some inexplicable reason, the BASIC tokens are differnntly ordered, so a binary BASIC program from a Dragon won;t load on a CoCo and vice versa... The main differece between the hardware of the Dragon and the CoCo is the printer port. There were 3 PIA lines left over once the necessary signal had been taken for the sound, cassette port, keyboard, VDG control, etc. As er all know, the CoCo used them for a bit-banged RS232 port. On the Dragon, they were the Strobe, Busy and ACK lines of a Centronics port. The data for that came from the 8 keyboard scan lines (one port of a PIA), suitably buffered. There was no problem with the dual use of this port, the machine didn't try to read the ekybaord inptus when it was sending a character to the printer, and the printer ignored the keyboard scan 'data' because there was no Strobe signal along with it. The Dragon 64 has (not surpisingly) twice as much RAM, and also a real hardware RS23 port, based IIRC on the 6551. Yes, I beleive so. -tony