On 1/30/2023 6:32 AM, Chris via cctalk wrote: Only DLOAD was implemented in BASIC, so two CoCos would not work.  As such, it did not get used and was eventually removed from the BASIC in the CC3. Cassette load was handled another way.  DLOAD specifically used the serial port. And yes, sending data to CoCo is not overly difficult, they were just wondering about the provenance and history of the DLOAD command in the BASIC. Jim

The cassette port on the Coco used two audio tones to represent binary data, 1200 HZ (1) and 2400Hz (0).  Each tone ran for some number of mS (I can't remember what the duration of the tones was). This was so that the cassettes could be duplicated on an audio tape duplicator and for noise immunity. The tape hardware/software had 3 bits, 1 for reading data, one for writing data and one to start and stop the tape.  A simple RC circuit provided additional noise immunity.  The software had to measure the the duration of the square wave for reading and make the square wave for writing. On 1/30/2023 11:14 AM, Chris via cctalk wrote:

On Mon, 30 Jan 2023, Jim Brain via cctalk wrote: The 5150 had a cassette port! Diagnostics were supplied on cassette tape. It was immediately adjacent to the keyboard port, and used the same 5 pin DIN connector, for the added convenience of being able to plug in to the wrong one. THAT mimiced the TRS80 model one, which had Power, video, and cassette in a group of three 5 pin DIN identical connectors. THAT, and the keyboards of the Jr and Coco, were to show that IBM was so big that it didn't have to learn from the misteaks of others. Since the 5150 cassette connector was the same 5 pin DIN as the TRS80, the source of cable for 5150 cassette was Radio Shack TRS80 cassette cable. There was an outfit that marketed a sorta network using the 5150 cassette port, for classroom distribution, etc. Adding 160K (and/or 180K,320K,360K with DOS 1.10 and 2.00) required the floppy disk controller board for about $300, DOS, and standard SA400 interface drives (such as borrowing from your TRS80); power connectors were already built in. So, few ever used the cassette port. It was months before after-market "multi-function" boards were available, so a 5150 consisted of main unit (~$1250), FDC (~$300), video board (~$300), monitor (CGA had compoosite output, so could connect to cheap CCTV, etc. monitors, and CGA even had a dedicated 4 pin Berg for the SupRMod RF adapter), and maybe serial, and/or parallel. The 5160 no longer had the cassette port. The 5150 cassette sorta network immediately disappeared from the market. -- Grumpy Ol' Fred cisin(a)xenosoft.com

On Mon, 30 Jan 2023, Paul Berger via cctalk wrote: Interesting! Was that stand-alone and compatible with the ordinary TDD/TTY units? (and coupled to a modem) Or was that solely for communicating with other 5150s? Or was that to use the 5150 as a KSR terminal for a TDD/TTY handling the POT communication? -- Grumpy Ol' Fred cisin(a)xenosoft.com

On 2023-01-30 1:50 p.m., Paul Berger via cctalk wrote: RTTY software might do that. Ben.

Hi Sent from the all new AOL app for Android On Mon, Jan 30, 2023 at 12:12 PM, Fred Cisin via cctalk<cctalk(a)classiccmp.org> wrote:>> The 5150 had a cassette port!>> . . .>> The 5160 no longer had the cassette port. On Mon, 30 Jan 2023, Paul Berger via cctalk wrote:> The cassette port on the 5150 could also be used as a Telecommunication> Device for the Deaf (TDD) many years ago I made up a ISA bus card with the> same function as the cassette port for a gentleman that wanted to move on> from a 5150 but still needed the cassette port for a TDD device. Interesting! Was that stand-alone and compatible with the ordinary TDD/TTY units?(and coupled to a modem)Or was that solely for communicating with other 5150s? Or was that to use the 5150 as a KSR terminal for a TDD/TTY handling thePOT communication? --Grumpy Ol' Fred cisin(a)xenosoft.com Was this to actually communicate with the true Deftones for tdd work if so I'd be real interested in it we have a very large collection of items that are assistive for the deaf and hard of hearing at smecc Museum and this would qualify for that so yeah tell me some more thanks Ed

For reference, my notes on the CTR/CCR tape units (and its relationship to CoCo's and the 5150): https://voidstar.blog/all-about-tandy-radio-shack-computer-cassette-recorde… (the Tandy Modem 1 from 1981 also used the cassette port, on one of the TRS-80 systems - at least per its manual) I know IBM had many NDA's when developing the 5150, and also that development was done as secretly and quickly as possible. I don't have any evidence for it, but I always assumed that IBM ended up "borrowing" the tape-cassette interface of the TRS-80, directly because of their relationship with Microsoft. Microsoft released TRSDOS Disk BASIC in 1979 - so they knew how to interface BASIC with disks. TRS-80 Model 3 release date was July 1980 CoCo release date is September 1980 I don't know exactly when the 5150 prototype started (there is an online claim about someone having "the" IBM 5150 prototype board - with a bunch of breadboard yellow wiring like they used on the 5100). There is a date on when IBM contacted Microsoft: July 21st, 1980 (Jack Sams call to Gates) -- same month as the TRS-80 Model 3 release. Then, about a week later: July 27th, 1980 is the date noted when Microsoft bought QDOS. So if Microsoft knew IBM was in a rush, and that IBM wouldn't want to R&D or consider any other new type of cassette-storage system (and there are QIC-based backup systems in early PC Magazine up to even '83 or '84 -- decent capacity, but still expensive as a standalone storage solution) -- Microsoft engineers probably suggested a design they were already familiar with. There was no serial port (on the 5150 mainboard). Maybe they used the tape system to bootstrap early BIOS or MS-DOS revisions? (the disk drive system hadn't been developed yet) OR, maybe use of the tape system was to distract anyone who might ask questions about the system (i.e. keep the system uninteresting). Did IBM also borrow aspects of the 5.25" disk drive system from the TRS-80 Model 3? Maybe not, if the ISA bus required something different for that. But to both Microsoft and IBM, "borrowing" the existing tape system from the TRS-80 seems like a logical decision (cheap, quick, and can test some stuff before the floppy disk solution was finished) - but it's just my speculation. -Steve

Fred, This is the first time I am hearing about this. I always thought the connector was for light pen input. -Ali

The 4 pin RF modulator conector is the same as what is on the Apple2 On Tue, 31 Jan 2023, Ali wrote:

On Mon, Jan 30, 2023 at 5:34 PM Jim Brain via cctalk <cctalk(a)classiccmp.org> wrote: Yes, all those have dedicated cassette ports. ZX80, ZX81, Spectrum, Acorn Acom, Acorn Electron, BBC Micro, etc, etc. Do you count machines like the Amstrad CPC464 which had a built-in cassette recorder? There was an almghty kludge in the TRS-80 Modem 1. You could flip a switch and the modem serial input changed from RS232 levels to cassette levels. The modem serial output became a keyed (by the serial data) audio tone. This meant you could link it to a Model 1 cassette port and drive it with special software. It's documented in the service manual for said modem. -tony

On Tue, Jan 31, 2023 at 10:56 AM Philip Belben via cctalk <cctalk(a)classiccmp.org> wrote: I think somebody else mentioned that one. When I got my first PET, I didn't have the Commodore casstte recorder for it. So I designed a simple interface to link a normal cassette recorder to the PET's edge connector. I used the motor drive line to operate a relay with the contacts going to the remote socket on the cassette unit. Since the cassette recorder I was using (a Radio Shack CCR-82) had the +ve battery line going to the internal on-off switch, then to the remote socket, then to the motor, I could sense the voltage on the appropriate side of the remote socket to indicate when the 'Play' key was pressed and use that to switch a transistor connected to the PET's cassette switch pin. Almost all 8-bit home micros bit-banged the tones, and also decoded them in software. I think the BBC micro (and Electron?) was the common exception in the UK. -tony

On 1/31/2023 6:04 AM, Tony Duell via cctalk wrote: It's always a possibility, but a dead test cart with the code would have been a far better solution, and easier to implement, as the ROM is permanent 9so to speak) on a home machine and would have had to go through more QA. I think (I might have mentioned it at the thread start) it was part of a plan for a school network.  Tandy offered a similar setup for schools for the Model 1/3/4 systems, where the "host" could send programs, and the clients would load from the common host system. Jim -- Jim Brain brain(a)jbrain.com www.jbrain.com

I worked with an elementary school teacher who used exactly such a system to ship software from a CoCo 3 with a floppy drive to diskless CoCo 2s. You turned the dial to each client in turn and ran CLOAD on the client, and it pulled it over the cassette port. No automatic push, but I think he had only around 15 computers or so, so it didn't take long to load software. My math fractions trainer I wrote in CoCo BASIC was in use there for a number of years. -- ------------------------------------ personal: http://www.cameronkaiser.com/ -- Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com -- Birth, n.: The first and direst of all disasters. -- Ambrose Bierce --------