Washington-In the aftermath of the electoral train wreck in Florida, localities around the country are taking a hard look at alternatives to punch-card balloting, with its potential for ambiguous chads, both dimpled and hanging.

But some computer specialists caution that electronic voting machines, widely discussed as an up-to-date alternative to paper ballot systems, have drawbacks of their own and are unlikely to become the dominant voting system in the United States any time soon.

 The machines can cost as much as $7,000 each, a substantial up-front investment that many counties and municipalities had been reluctant to consider.

Estimates of the cost of installing the so-called "direct entry" electronic machines nationwide vary widely, depending on their capabilities. One industry official estimated that it could cost $3.5 billion. R. Doug Lewis, executive director of the Houston-based Election Center, an international association of election officials, said it could be as high as $9.5 billion.

The electronic machines, with touch-screen displays of candidates' names, record a voter's selections directly into computer memory. They are used by about 9 percent of the nation's voters, according to 1998 statistics compiled by Election Data Services, a consulting firm in Washington, D.C.

In contrast, about one third of the nation still votes with punch-card ballots like those at the center of the Florida controversy. Another 27 percent use paper ballots on which voters fill in their choices with a pencil or other marker. Those ballots are then "read" by an optical scanner during tabulation.

The direct-entry electronic machines are touted as having less potential for ambiguity than paper ballot systems. Like the old mechanical lever machines still used in New York and elsewhere, the direct-entry electronic machines prevent debate on a voter's intent - once the touch screen selections are made or the mechanical levers are pulled, the vote is entered. No hanging chads. No incompletely filled-in boxes that might be missed by the optical scanner. No double voting.

But, beyond the issue of cost, some computer experts argue that the direct-entry electronic machines are not foolproof either and do not produce what they consider an adequate "audit trail"-a physical record of each ballot cast-in the event of a challenged election. Critics also have raised questions about the security of the machines and the susceptibility of their complex software to mischief, either by an insider or a determined hacker.

New York City spent nearly a decade in an effort to purchase electronic voting machines from Sequoia Pacific of Jamestown, N.Y., with Deloitte & Touche as a subcontractor. The city finally decided the design of the proposed $60-million system, involving about 7,000 machines, was too flawed to proceed. The company took the city to court, and the contract-after $17 million in city funds had been spent-was abandoned this summer with $472,000 paid as a final dispute settlement.

Peter Neumann, a computer security specialist for SRI International in Menlo Park, Calif., served as a consultant to the New York City Board of Elections. He was allowed to examine part of the proprietary software, also called source code, for the machines.

"Even though we looked at their source code in some detail, and the source code looked pretty good, we produced a report that had a long list of ways the system could be corrupted, subverted or defrauded," Neumann said. He declined to go into specifics, citing a non-disclosure agreement he signed with the the city. But Neumann said "there is no such thing as a secure operating system. If you have insider misuse, all bets are off. You can rig anything."

Phil Foster, a regional manager for Sequoia Pacific based in Birmingham, Ala., said the New York City contract faltered over "a number of very complex contract issues." He defended the security of the electronic voting machines and said he could not envision circumstances in which an insider, working alone, could program the machines to rig an election.

"There is security in redundancy," Foster said. "Each voting machine is a stand-alone computer. They are not all hooked into one system." He said the software instructions that drive each machine are held in "read only" memory in the machine's central processing unit. Foster said there are no inputting devices on the voting machines that would allow a poll worker or others to tinker with the pre-programed operation of a particular machine.

Specialists say they know of no disputes involving electronic voting machines comparable to the challenges involving paper ballots in Florida. But they said the very nature of the machine operation- with votes entered and stored through the movement of electrons in a computer's micro-circuitry- would make it difficult to determine if there had been subtle tinkering with a machine or machines to add a vote here and there for a particular candidate. As Neumann puts it, "in electronic voting systems, dirty tricks may be indistinguishable from accidental errors."

Howard Cramer, a Denver-based sales manager for Sequoia Pacific, said there is a good reason to use software that is closely held. "If we were using Windows 95 as an operating system, how vulnerable does that become?" Cramer said. "That would be a terrible choice for us to make. Having an operating system of proprietary nature is an extremely useful first line of defense against hackers, introduction of viruses and other doomsday scenarios."

Still, critics say the confidential nature of the software used in direct-entry electronic voting machines, which started to come into widespread use about a decade ago, makes it difficult to do an outside assessment of the machines' security and reliability. The National Association of State Election Directors does oversee testing and qualification of voting equipment, both hardware and software. While some specialists have questioned whether the software testing offers sufficient assurance, Lewis of the Election Center said it is rigorous.

"They certainly have software tools that they use to check the lines of code to make sure they don't end up with unintended results," Lewis said. They go through it to make sure there are reasonable protections to prevent 'Trojan horses and viruses."

But skeptics remain.  "A lot of the issues that were raised 10 years ago are just as relevant today," said Howard Jay Strauss, a Princeton University computer specialist. "The software remains behind closed doors."

While casting and counting votes would seem like a straghtforward task for computer programers-just tally the vote and keep adding one in the appropriate column-Strauss said the software for electronic voting machines involves tens of thousands of lines of instruction code. It must be able to account for such situations as multiple- party balloting, cross-filed candidates, straight-party voting, lockout of non-eligible voters in primary races and split precincts.

An undetected error in software could lead to miscounted ballots, experts said. Neumann said high-assurance software systems are costly and still remain vulnerable to manipulation.

"I and many 12-year-olds can write a program that would print one thing on the screen and a different thing in the ballot cartridge" that records the votes in an electronic voting machine, said Rebecca Mercuri, a specialist on voting machines who teaches computer science at Bryn Mawr College in Pennsylvania.

Electronic voting machines typically retain a record of a voter's selections both in a machine's hard drive and in a removable memory cartridge. The machine can print out a paper record of the data, Foster said, with the sequence of votes randomized to prevent potential identification of voters by their time of voting. But Mercuri and others argue that such a record is not the same as individual paper ballots that can be kept for later review and manual recount if needed. She advocates adding a feature to the electronic machines: After a voter enters touch-screen selections, the machine also would produce a printout of the ballot choices, which the voter would verify and place into a secure ballot box as a backup.

Roy Saltman, who wrote an influential 1988 report on voting systems for the National Institute of Standards and Technology, said he is not aware of any major problems with electronic voting systems. He said he saw no reason to produce an individual paper record of each vote cast on an electronic machine.

Lewis of the Election Center said next-generation electronic voting machines could be designed to provide such a paper trail. They also will be more capable of serving the needs of diverse voters, including the blind and the physically disabled, he said. But such machines would be expensive- he estimates a price tag of $9.5 billion to outfit precincts nationwide with them.

Onething seems clear,according to the experts. The days of the punch-card ballot are probably numbered. Saltman, who is now retired, called for its elimination in his report a dozen years ago. "Now that it has gotten on the national radar screen, which it never had been before," Saltman said, "I think election administrators will be embarrassed to continue using it."

Manufacturers of electronic voting machines say they have seen an upsurge in inquiries from election officials about newer voting systems in the wake of the Florida voting experience.

"The phones are ringing off the hook," said Jeff Crider, a spokesman for Sequoia Pacific. "The interest has just been phenomenal."

But whether that interest will translate into real purchases after dust settles from the tight presidential election remains to be seen. The Sequoia Pacific machines range in price from about $3,700 to $5,400 per unit, according to Foster.

Todd Urosevich, a customer support specialist for Election Systems & Software, Inc. of Omaha, Neb., said his firm makes two types of electronic voting machines: a touch-screen model (with a display similar in size to a banking ATM ) that allows the voter to scroll through successive screens with voting choices; and a full-face machine that allows display of an entire ballot on one screen. The full-face machine is roughly double the cost of the unit with the smaller screen- $6,000 to $7,000 per machine compared to about $3,500 per machine for the smaller units.

Urosevich said his company also has been gt electronic voting machines. "I wouldn't call it an avalanche yet," Urosevich said. "The real proof will be down the road when state legislators get together and begin to think about funding."

Foster of Sequoia Pacific said hisback-of-the-envelope guess on the cost of putting electronic machines into every voting precinct is about $3.5 billion. But he said he and others said they know of no detailed estimates of the cost, which would include support services for installation of the machines and training of personnel.

Foster said that he spent more than 100 days in Riverside, Calif. alone when he managed the installation of an electronic voting system in that city. In any event, the industry as now constituted would be unable to handle any massive effort to install electronic machines nationwide. "If you broke it up to all the vendors in the market today, I don't think they could get it all implemented in 4 years," Foster said.

Lewis agreed. "If you took the combined resources of all the manufacturers of voting systems and put their production into high gear, you might be able to do it within six years."

More likely, Lewis and others said, election officials will look for less radical alternatives that address the concern over punch-card ballots without breaking the budget of local jurisdictions.

Sen. Charles Schumer (D-N.Y.) has introduced legislation to pay for a Federal Election Commission study of alternative voting methods and to establish a $250 million fund to help states modernize their systems. The bill, co-sponsored by Sen. Sam Brownback (R-Kan.), has bipartisan support, Schumer said last week.

"Despite over two hundred years of elections, we vote as if we still live in the 19th Century," Schumer said. The legislation calls for study of computerized voting machines, voting by mail, Internet voting, redesigned ballots and expanding or changing the hours of voting, among other possibilities.

Schumer said the $250 million would not be enough for a national revamping of the voting system, which he said could cost about $1 billion. Schumer said that estimate assumes a mix of different systems, including the less pricey "marksense" systems with paper ballots that are optically scanned. The scanners can cost $6,000 each, but counties typically may have to buy only one per precinct (or fewer) compared to one of the electronic voting machines for every 250 or 300 voters.

Cathy Cox, the Georgia Secretary of State, said her office has been looking into the cost of outfitting more than 2,500 voting precincts in the state with direct-entry electronic voting machines. "It would be a distinct advantage to have one system throughout the state," Cox said. The estimates have run from about $40 million to as high as $200 million, she said. Right now, 73 counties use the mechanical lever machines, 17 use punch cards and two still use paper ballots on which voters mark boxes next to a candidate's name. Cox said she is just as concerned about replacing the mechanical lever machines as the controversial punch-card systems.

When the levers are pulled, the running vote count is kept by devices in the machine that look much like an automobile odometer. It is possible, Cox said, for one of the counting devices to fail without warning. "A wheel didn't turn and no whistle had gone off to make you aware of that during the day, and so you've lost all those ballots and there's no option for a recount or reconstructing those ballots. They are just lost." That prospect, she said, "just frightens me to death."

New York election officials say the lever machines in use in the state are well-maintained and checked out before each election. But most of the lever machines are more than 30 years old, experts say, and no new models are being made. It is only a matter of time, they say, until the machines can no longer perform up to 21st Century : standards for reliability and accuracy.

Caption: 1) AP Photo - Florida's punch-card ballot problem has led some to call for better alternatives for voters. 2) Los Angeles Times Photo/Tracy Lee Silveria - Marilyn Pendergrass, 74, of Riverside, Calif. was a bit apprehensive at first about voting electronically but was delighted by its simplicity.