Commodore 1570 disk drive

The Commodore 1570 disk drive was an odd, short-lived product from Commodore in 1985. Like many things Commodore did that year, it solved an inventory problem for them, but can leave people scratching their heads today.

The Commodore 1570 looks like a mashup between the 1541 and 1571 drives, and that’s exactly what it is. It’s a fast 1541 designed for the Commodore 128.

Commodore’s inventory problems

Commodore 1570 disk drive
The Commodore 1570 disk drive was the result of combining surplus 1541 drive mechanisms with 1571 motherboards to solve supply issues.

In 1983, Commodore had 1/3 of the fast growing computer market all to itself. It fought off challenges from larger companies with better name recognition, and its future looked bright.

But Commodore went from selling Commodore 64s and 1541 disk drives faster than it could make them to a disappointing 1984. Much of this was Commodore’s own fault.

Its rapid price cuts led to the video game crash of 1983 and vanquished several competitors, but it also weakened Commodore. The price cuts undermined the perceived value of its computers. And someone forgot to send the memo to Commodore’s management that they won in 1983. Commodore spent 1984 competing with itself, launching the Plus/4 and 16 to compete with the Timex-Sinclair 2068 after Timex discontinued it. With nothing else to compete with, those two machines ended up competing with the Commodore 64.

In 1985, Commodore juiced its sales with the Commodore 128. It wasn’t anyone’s first choice, but the Amiga wasn’t ready. The 128 gave Commodore a mid-priced machine to sell in the interim. It was a nice upgrade for 64 owners, with backward compatibility, a faster CPU, and a faster disk drive.

But the disk drive proved to be a problem.

Enter the 1570 disk drive

Commodore also designed a fast, high-capacity double-sided disk drive to go with the 128. It called it the 1571. The 128 sold well, but Commodore didn’t have enough disk drives. Some people were willing to make due with a 1541, but the faster disk drive was one of the 128’s big selling points.

In August 2020, retro computing Youtuber Adrian Black made a video about the 1570. He acquired a 1570 from a viewer in Germany, and in the process of converting it to run on US power, he expressed confusion about what the drive was and what purpose it served. Externally, it looks like a 1541 painted up to match a 128. Internally, it’s a mess. Inside, it’s a 1541 drive mechanism and power supply, with a 1571 motherboard turned sideways to fit, with a mess of wires strewn all over the place to make the board work with a drive mechanism and enclosure it wasn’t designed for. It looked like a lot of trouble and a lot of unnecessary expense.

Later that month, Commodore historian Dave McMurtrie released a single page excerpt from a 1985 strategic plan he acquired, presumably from a former Commodore employee. The page detailed the reasoning behind the 1570. Commodore could only get enough drive mechanisms to produce 250,000 1571s in the second half of 1985. But Commodore had 220,000 surplus 1541 drive mechanisms. The memo stated drive heads, but I think the author meant mechanisms, not heads, because Commodore bought full mechanisms, not individual components. Commodore rigged up those surplus 1541 mechanisms to work with a 1571 board, painted the mechanisms beige to match the 128, and put it in a 1541-style case molded from the same plastic as the 128 and 1571. Commodore sold the 1570s in Europe and the 1571s in North America to try to meet demand.

The design changes increased the cost, but it allowed Commodore to quickly liquidate $8 million worth of parts. And if demand warranted, Commodore could convert unsold 1541s to 1570s in 1986.

Commodore 1541 vs 1570

The 1541 was Commodore’s primary disk drive for the C-64. I can attest we loved to hate it. On the outside, the 1541 and 1570 look like twins. The 1570 literally looks like a 1541C with an Alps drive mechanism and a different label. And if you use it with a C-64, there is no difference. It runs in 1541 emulation mode, and if you change it to its native mode, it’s just a not-quite-fully-compatible 1541.

The differences are internal, and they only help you if you’re using a C-128.

Inside, the 1570 has a slightly modified 1571 motherboard in it with a dedicated 6502 CPU, 2K of RAM and 32K of ROM, a pair of 65C22 VIAs and a 6526 or 8520 CIAs to implement Commodore’s IEC bus with burst mode, and a WD1770 or 1772 controller for MFM compatibility.

When you use it with a 128, it’s just a 1571 with half the capacity. It’s exactly the same speed as a 1571, and can use either GCR or MFM disks. In the 128’s CP/M mode, the 1570 can read foreign disks such as Kaypro and Osborne, as long as they’re single-sided.

There’s another difference too. The 1541C used an off-white drive mechanism that matched the 128 and 64C. The 1570 used up Commodore’s existing supply of older 1541 Alps mechanisms. Commodore painted them to match the case. Frequently when you find a 1570 today, the paint is worn off a bit, revealing black plastic underneath.

Converting 1541 parts into a 1570 cost money, but the 1570 could retail for more than a 1541 did, so it was easy enough for Commodore to recoup the costs.

Rarity

Commodore 1570 disk drives aren’t common. Commodore only sold them in Europe, and only until it used up its 1541 parts inventory. Theoretically, there could be as few as 220,000 of them in existence. It’s more common than the 1581, but less common than the 1541 or 1571. It’s unclear how many 1541s Commodore had to convert to 1570s, because the 128’s success also had the side effect of increasing C-64 and 1541 sales.

The 1570 disk drives rarely turn up in the United States, as Commodore didn’t market them here. When they turn up on Ebay, they often sell for less than a 1571, but that may be because not as many people know what they are. If you’re in the United States and want one, keep in mind the shipping from Germany won’t be cheap, and you’ll have to convert the drive to run on US power. The easiest way to do this is to swap the lower chassis with a 1541, ideally a 1541 with a shorted drive head. About half the 1541s with Newtronics drive mechanisms I’ve seen have shorted heads, so they’re good donor candidates.

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