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What happened to the cassette interface from the IBM 5150?

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Scali

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The original IBM 5150 had a cassette interface, as most of you probably know.
The PCjr also had one (which was compatible afaik).
But on the 5160 it was removed... and we have never seen it again.
Playing around with my 5160 the other day, I accidentally got it to boot in ROM BASIC, because the floppy wouldn't boot.
Which popped up the following questions:
1) Are there any PCs outside the 5150 and the PCjr that have the cassette interface?
2) What does it take hardware-wise to add a cassette interface to a 5160, or possibly any generic clone?

I already found this thread: http://www.vintage-computer.com/vcforum/showthread.php?8829-IBM-PC-Cassette-interface/page2
It speaks of some Soviet PCjr clone, which also had the cassette interface?
Also, it says that the tape interface was just driven off the interrupt timer and the 8255, so it doesn't require a separate controller. It's basically wired up in the PC speaker circuit. As I also understand from this schematic: http://www.minuszerodegrees.net/5150/misc/5150_speaker_circuit.jpg

So that would mean that you could probably modify a 5160 or clone board to add a cassette interface? Has anyone ever tried this?
 
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I've heard (but not confirmed) that the original Compaq Portable was designed to have a cassette interface, but it wasn't installed in the production model, so there are some unused traces and component holes on the motherboard.

IBM kept Cassette BASIC in ROM for a long, long time. I've even seen it in an Aptiva model from the mid-'90s.

I've even seen XT clones with IBM ROM BASIC (illegally copied, of course).
 
vwestlife said:
IBM kept Cassette BASIC in ROM for a long, long time. I've even seen it in an Aptiva model from the mid-'90s.
Click to expand...

Yes, from what I understood, the reason for that was that their DISK BASIC and BASICA were actually extensions of the ROM BASIC rather than standalone (like GW-BASIC), so without the ROM, these BASICs will not function.
I wonder why IBM stuck with that approach though, since GW-BASIC was available anyway, and used on all clones.
 
Scali said:
Yes, from what I understood, the reason for that was that their DISK BASIC and BASICA were actually extensions of the ROM BASIC rather than standalone (like GW-BASIC), so without the ROM, these BASICs will not function.
I wonder why IBM stuck with that approach though, since GW-BASIC was available anyway, and used on all clones.
Click to expand...

The first version of IBM DOS 5.0 had a copy of QBASIC that required ROM BASIC to run. But later IBM patched it to no longer require ROM BASIC.
 
Caluser2000 said:
I guess the first question you have to ask is why was the cassette drive interface dropped in the first place?
Click to expand...

Well, I am from the "cassette generation" as I started out with a ZX81 and then a C64, both with cassette...
However, as soon as I had my 1541 floppy drive for my C64, the cassette never saw any use again :)
Cassettes are just horribly inconvenient, and the only reason we used them was because floppy drives were prohibitively expensive in the early days.
I suppose by the time the 5160 was introduced, floppy drives had become commonplace anyway. So removing the cassette interface was a nice way to shave a few bucks off the total cost of the machine?

Unless there is another reason?
 
Sounds reasonable and makes sense.

As for why IBM kept going with Cassette Basic in rom? Backwards compatibility I'd imagine, it was also in their PS/2 line. Having their own Dos "distro" if you will which was for IBM kit only usage having BASISA/DISK BASIC tied into the rom BASIC most likely made sense to them.
 
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The 5150 could initially be bought as a budget release without floppy drives, and then casette would then be the only alternative storage medium. It's also importaint to keep in mind that IBM didn't exactly have any expectations that the market would react the way it did, and that the PC was only designed as an experiment for them to check out the microcomputer market.

When the XT came around the PCjr was intended to take over the portion of the market previously held by the non-floppy release of the PC, and as mentioned floppy drives were cheaper as well.
 
per said:
When the XT came around the PCjr was intended to take over the portion of the market previously held by the non-floppy release of the PC, and as mentioned floppy drives were cheaper as well.
Click to expand...

Or, the easy answer is that they left off the cassette port on the XT to make room for the 3 extra expansion slots. :)

Pretty much the only real practical use the cassette port on the PC and PCjr ever got was toggling the MOTOR command in BASIC programs to make clicking and buzzing sounds!

 
Consider--the cassette interface was slow (about 1500 bps, IIRC) and consecutive-access. Floppies were still pretty expensive, IIRC--I think the FDC and single-sided floppy added about $300 to the cost of my 5150. Cassettes aren't particularly reliable, although there was a move in the early 70s to replace paper tape by cassette--and there were digital (not analog) cassette drives--I had a two-drive unit from Techtran that supported high-speed search and copy as well as speeds up to 9600 bps. Attempts were made to take the technology and move it a bit more into the mainstream (cf Extatron "stringy floppy"), but ultimately the lack of random access and rewrite doomed the media.

My last run-in with audio cassette technology was the Datasonix Pereos drive in the 1990s, which used the Sony 2 mm micro-cassettes. I believe that the claim was 1GB per postage (airmail-sized) cassette.
 
vwestlife said:
Or, the easy answer is that they left off the cassette port on the XT to make room for the 3 extra expansion slots. :)
Click to expand...

They just reduced the spacing between the expansion slots.
There would still be enough space between the keyboard connector and the nearest ISA slot to have a cassette port on the 5160. Alternatively they could stack the two ports on top of eachother, or use a header on the motherboard and have chassis-mounted ports connected with a ribbon cable or such.
 
Chuck(G) said:
Attempts were made to take the technology and move it a bit more into the mainstream (cf Extatron "stringy floppy"), but ultimately the lack of random access and rewrite doomed the media.
Click to expand...

Well, tapestreamers have been around as backup media for many years. I still had a QIC-80 tapestreamer somewhere in the late 90s, because it was a cheap, convenient and reliable way to store and share large amounts of data.
 
vwestlife said:
The first version of IBM DOS 5.0 had a copy of QBASIC that required ROM BASIC to run. But later IBM patched it to no longer require ROM BASIC.
Click to expand...
This was a software protection scheme to ensure that QBASIC would only run on legitimate PCs, XTs, and ATs. More info (and a TSR I wrote to bypass it) here.

I've never actually seen an IBM cassette recorder/player- or one with a DIN5 connector, for that matter.
 
cr1901 said:
This was a software protection scheme to ensure that QBASIC would only run on legitimate PCs, XTs, and ATs. More info (and a TSR I wrote to bypass it) here.
Click to expand...

Yup... It's just that it doesn't make a lot of sense when MS supplies GW-BASIC and QBASIC anyway, for clones. Which are identical, except that the ROM-code is not required.

cr1901 said:
I've never actually seen an IBM cassette recorder/player- or one with a DIN5 connector, for that matter.
Click to expand...

From what I understood, IBM did not produce a cassette recorder themselves, or even a cable. I heard that the TRS-80 cassette unit was a common option. But really any generic cassette recorder with a line-in or mic-in and a line-out/headphone-out could be used.
I had the same on my handmade ZX81-clone. It just used a generic Philips memo recorder (would need external power supply, and obviously would not respond to motor on/off signals).
 
Scali said:
I heard that the TRS-80 cassette unit was a common option.
Click to expand...
It's pin to pin the same cable, so the CTR-80 and CCR-81 are fine choices.

8 bit micro has the wiring up on their site:
http://www.8bit-micro.com/data-cable.htm

About a year ago I picked up one of these on sale at Walmart for $20 (their current price is nutters)
http://www.walmart.com/ip/RCA-RP3504-Cassette-Shoebox-Voice-Recorder/40182268

Which is a great choice if you need a new one as it has a working 1/16th "remote" connection, something a lot of post 1980's recorders lack.
 
deathshadow said:
Which is a great choice if you need a new one as it has a working 1/16th "remote" connection, something a lot of post 1980's recorders lack.
Click to expand...

Yes, isn't that normally connected to a button/switch on the microphone? Basically toggle the power to the motor, so it starts/stops recording.
Where do these CTR-80/CTR-81 get their power from though?
I was thinking, a Commodore Datasette wound be an interesting mod. It takes the power from the C64. I guess you could take power from a COM/LPT/keyboard port on PC, and then make a simple circuit on the remote to control the motor that way. Then it's powered completely by the cable itself, no fuss with batteries/power supplies.
 
Scali said:
Well, tapestreamers have been around as backup media for many years. I still had a QIC-80 tapestreamer somewhere in the late 90s, because it was a cheap, convenient and reliable way to store and share large amounts of data.
Click to expand...

You miss the point--I'm talking about cassette units using audio tape. The Techtran unit was one such--I still have an "digital audio" tape in a Philips-type cassette from NCR. The Techtran unit was not only NRZI recording, but the tape decks themselves were no-capstan dual-servo hub motor units (the tape data was 2-track; one clock one data). The aforementioned Pereos unit was built from sub-micro-audio cassette pocket dictation unit transport:

ndc-04.jpg


Ran from 2 AA cells; parallel interface; one cartridge held 1GB (more or less). This is the last that I know of where an audio mag tape cassette was used for data. Very much akin to the Convergent Workslate:

thm_convergent-technologies_workslate_2.jpg


CD-ROMs and DAT started out as audio format media as well, but they're not analog. However, the connect-your-system-to-a-VHS recorder for backup could also be in the running.
 
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