Jack Tramiel, founder and driving force behind Commmodore, has resigned as its chief executive offices, and will cease to be a director. In a surprise announcement, the company said, although leaving the company he will continue to assist as a consultant and advisor.

Mr. Tramiel said only: "Personal reasons prevent my continuing on a full-time basis with Commodore."

He will be replaced by Marshall F. Smith, currently president of Thyssen-Bornemisza, an industrial conglomerate involved in everything from soft drinks packaging to the manufacture of car parts.

Irving Gould, Commodore's chairman, praised Mr. Tramiel's contribution to the company. "Under Mr. Tramiel's management and guidance, a very strong and talented primary and secondary management structure at Commodore has been put in place," he said.

Despite the compliments, reports from the US suggest Jack Tramiel's departure was forced on him in the wake of continuing complaints from employees and shareholders about his autocratic and idiosyncratic management style.

Over the last three years, three presidents and numerous senior staff, including marketing executives, have been sacked by Tramiel and others have left of their own accord.

According to one report it was the possible recruitment of Mr. Smith to run Commodore's international business that led to Mr. Tramiel's department. Mr. Gould wanted to appoint Mr. Smith to the post but he was reluctant to take the job while Mr. Tramiel was still in overall charge.

Commodore's UK successors to the 64 will be similar to two machines it exhibited at the Consumer Electronics Show in Las Vegas earlier this month.

The two new machines are likely to be in the £400-plus range and aim to compete with the bottom end of the business market. They will have 32K ROM and 64K RAM, an extraordinary 60K of which is user-addressable.

As yet it isn't clear to what extent the new systems are expected to replace the 64, which is barely a year old in this country and which has been a spectacular success. US observers had expected a Commodore 128, but as usual the company has caught them on the hop.

The two machines were shown in the US under the names 264 and V364. But only the C364 is lekly to be sold under the same name here. John Baxter, marketing manager of Commodore (UK) explained there are currently at least seven options open to Commodore for the exact specification of the smaller machine, and that final decisions were still being made.

One or both of the new machines will probably feature the Magic Voice speech chip built-in, and both machines will have new keyboards. The V364 will have more keys than the smaller machine, and also a separate numeric keypad as standard. In common with just about every other new micro on the market, the new Commodores will have extended Basic - probably Basic 4, the language in Commodore's range of business machines.

Due to the nature of the new language and the new chip used (the 7501) the new machines will be compatible with neither the Vic 20 or the Commodore 64, enabling Commodore to keep faith with a long standard tradition.

Commodore plans to have the 264 and V364 on sale in the US from April 1 1984, and in the UK from May or June.

• Commmodore is also preparing to announce a new 1Mb 5.25" disk drive, though this will probably not be available in the UK for some months. It is expected to retail at about £570. Commodore's choice of 5.25" technology is mysterious when so many manufacturers are now moving on to the more reliable 3"/3.5" drives.